Use these selected concepts to connect tissue findings with clinical presentation, investigations and diagnostic decisions. Each concept includes a worked interpretation and a specific error to avoid. The guide addresses candidates for the combined oral medicine and oral pathology pathway of the National Dental Specialty Examination.
Foundational biomedical mechanisms
1. Platelet aggregation and fibrin stabilization
Antiplatelet drugs inhibit platelet aggregation steps needed for primary haemostasis; anticoagulants inhibit coagulation-cascade factors, impairing the fibrin-stabilized secondary haemostasis. This mechanism distinction alone does not establish whether medication should be interrupted for dental treatment.
Worked example: A patient on warfarin has impaired coagulation-factor function affecting secondary haemostasis, while another patient's antiplatelet drug impairs platelet aggregation and primary haemostasis; this mechanism difference alone does not establish whether either medication warrants interruption.
Mistake to avoid: Describing warfarin's anticoagulant action as inhibition of platelet aggregation rather than impaired coagulation-factor function.
Reference: [15]
2. Saliva as a protective oral fluid
Saliva cleanses the oral cavity, facilitates sugar clearance, buffers acids, and its proteins and mucins lubricate and coat tissues; reduced flow can therefore affect teeth and mucosa, not just moisture. Such findings support salivary assessment without identifying the cause of reduced flow.
Worked example: A patient presents with cervical caries and difficulty swallowing; these findings warrant assessment of salivary function, though they do not by themselves identify why flow is reduced.
Mistake to avoid: Teaching that saliva's only role is keeping the mouth wet, ignoring buffering and clearance.
Reference: [13]
3. Candida colonization and immune suppression
Candida organisms are common commensals on healthy mucosal surfaces, but oropharyngeal or esophageal candidiasis in adults and adolescents with HIV is recognized as an indicator of immune suppression; colonization alone proves neither infection nor HIV.
Worked example: An asymptomatic patient whose mucosal culture grows Candida shows colonization, whereas an adult with HIV presenting painless creamy white plaques and odynophagia has characteristic disease that may indicate immune suppression.
Mistake to avoid: Treating any Candida isolate from mucosa as proof of symptomatic infection or HIV infection.
Reference: [12]
4. Anticholinergic medication and oral dryness
The medications most commonly causing salivary dysfunction have anticholinergic effects, such as tricyclic antidepressants and antihistamines, and patients taking multiple medications may be at higher risk of dry mouth; exposure is a possible contributor, not proof of sole causation.
Worked example: A patient newly reporting dry mouth takes a tricyclic antidepressant and an over-the-counter antihistamine; both are reviewed as possible contributors during assessment, without recommending any change to prescribed medication.
Mistake to avoid: Attributing an older patient's dry mouth to age alone without reviewing medications and diseases.
Reference: [13]
5. Excess parathyroid hormone and bone resorption
The teaching passage focuses on primary hyperparathyroidism, where excess parathyroid hormone drives generalized bone resorption, especially in small bones such as the jaws, and may produce multiple bone lesions indistinguishable from central giant cell granuloma. A complete endocrine diagnosis requires appropriate systemic evaluation; PTH alone is not a universal classification rule.
Worked example: A middle-aged woman's giant cell jaw lesion is interpreted alongside her elevated serum PTH result, prompting systemic endocrine evaluation rather than an isolated intraosseous diagnosis of a primary giant cell granuloma.
Mistake to avoid: Diagnosing every giant cell jaw lesion as a primary local granuloma without checking the parathyroid hormone level first.
Reference: [8]
Jaw lesions and integrated diagnosis
6. Glandular odontogenic cyst lining
Glandular odontogenic cyst is an odontogenic cyst, not a salivary gland cyst, and its misleading name reflects distinctive lining histology: stratified squamous epithelium covered by cuboidal or columnar cells, sometimes ciliated, interspersed with microcystic spaces simulating salivary gland ducts. Evaluate the complete lining and clinicoradiographic context before considering this diagnosis.
Worked example: A cyst biopsy from an adult's anterior mandible shows squamous lining with surface cuboidal cells and duct-like microcystic spaces, so the pathologist considers glandular odontogenic cyst within the full clinicoradiographic picture.
Mistake to avoid: Calling the lesion a salivary gland tumour simply because duct-like microcystic spaces appear within the cyst lining.
Reference: [8]
7. Brown tumour versus central giant cell granuloma
A hyperparathyroidism-associated giant cell lesion (brown tumour) is histologically indistinguishable from central giant cell granuloma, so tissue morphology alone cannot establish the etiology. This distinction requires laboratory and clinical correlation, and the hyperparathyroidism subtype must not be inferred from the tissue's microscopic appearance.
Worked example: A jaw giant cell specimen is reported as microscopically matching central giant cell granuloma; because the patient's PTH level is elevated, the pathologist correlates laboratory and clinical findings before any etiologic diagnosis is assigned.
Mistake to avoid: Assigning a definitive central giant cell granuloma diagnosis from histology alone, ignoring the patient's elevated PTH result.
Reference: [8]
8. Odontogenic keratocyst growth pattern
Odontogenic keratocysts may grow substantially along the jaw, typically penetrating bone rather than expanding it and extending in an anterior-to-posterior direction, often while remaining asymptomatic. Expansion and multilocularity can occur, and this growth pattern supports a differential diagnosis but does not replace histologic diagnosis.
Worked example: A posterior mandibular radiolucency extends longitudinally toward the ramus with little visible swelling, so the clinician retains odontogenic keratocyst in the differential while awaiting histologic confirmation of the diagnosis.
Mistake to avoid: Assuming a posterior mandibular radiolucency with minimal swelling must be small, inactive, or non-aggressive.
Reference: [8]
9. Benign but locally aggressive ameloblastoma
Ameloblastoma is a slow-growing, persistent, locally aggressive odontogenic epithelial neoplasm. Despite its benign classification, it can loosen, displace and resorb adjacent teeth and perforate bone, so benignity does not guarantee harmless local behaviour.
Worked example: A multilocular, expansile mandibular radiolucency that has resorbed molar roots and thinned the cortical plate remains compatible with ameloblastoma, showing that a benign diagnosis can still produce destructive local effects.
Mistake to avoid: Calling an ameloblastoma harmless on a report because the word benign appears in the diagnosis.
Reference: [8]
10. Mineralized lesion contents versus bony septa
Internal bony septa dividing a radiolucency are not the same as hard tissue produced by the lesion itself. Imaging interpretation must establish what an opacity represents before a lesion is treated as genuinely mixed radiolucent-radiopaque.
Worked example: A multilocular radiolucency whose compartments are separated by residual bony septa is not equivalent to a lesion containing true radiopaque deposits, so non-hard-tissue-producing lesions such as giant cell granulomas stay in that differential.
Mistake to avoid: Adding mineralizing tumours to a differential just because a radiolucency shows internal bony septa.
Reference: [9]
11. Central odontogenic fibroma in a mixed lesion differential
Central odontogenic fibroma is an uncommon odontogenic neoplasm of mesenchymal origin. It presents as a radiolucent or mixed radiolucent-radiopaque lesion, may produce flecks of hard tissue, and can resorb and displace teeth while growing slowly.
Worked example: A slowly enlarging jaw lesion with expansion, displaced teeth and scattered mineralized flecks on imaging supports including central odontogenic fibroma in the differential, though these features alone do not confirm the diagnosis.
Mistake to avoid: Dropping central odontogenic fibroma from consideration because the lesion is not purely radiolucent.
Reference: [9]
12. Cystic and solid ghost cell lesions
The calcifying odontogenic cyst spectrum includes a simple cyst, a cyst with an odontoma, a cyst with ameloblastomatous proliferations, and a distinct, least common solid odontogenic ghost cell tumour that behaves more aggressively than the cystic variants.
Worked example: A report describing a solid ghost cell neoplasm should not be read as equivalent to a simple calcifying odontogenic cyst, because the solid type is the least common variant but behaves more aggressively than the others.
Mistake to avoid: Assuming every ghost cell lesion behaves like a simple cyst and planning follow-up identically for all.
Reference: [9]
13. Calcifying epithelial odontogenic tumour
Calcifying epithelial odontogenic tumour (Pindborg tumour) is rare, clusters around 30-50 years, and most often occurs in the posterior mandible. It expands the jaw and resorbs or displaces teeth, behaving as a benign but locally aggressive neoplasm despite producing radiopaque mineralization.
Worked example: A painless, expansile posterior mandibular swelling in a 40-year-old shows a multilocular honeycomb radiolucency containing radiopaque flecks, with an adjacent molar displaced and resorbed; CEOT belongs on the differential.
Mistake to avoid: Assuming that radiopaque mineralization within an odontogenic jaw lesion guarantees a harmless, non-aggressive diagnosis.
Reference: [9]
14. Juvenile ossifying fibroma variants
Juvenile ossifying fibroma has trabecular and psammomatoid histologic variants with different usual sites and ages: trabecular favours the jaws in younger children, while psammomatoid occurs more commonly in the paranasal sinuses of older children and young adults. Both remain benign but locally aggressive.
Worked example: A sinonasal expansile mass in a 20-year-old raises consideration of psammomatoid juvenile ossifying fibroma, while an atypical jaw site or older age does not by itself exclude either variant.
Mistake to avoid: Excluding juvenile ossifying fibroma from a sinonasal differential because the patient's age exceeds the usual range.
Reference: [9]
Mucosal and infectious disease
15. Pemphigus vulgaris and epithelial acantholysis
Pemphigus vulgaris is a serious, potentially life-threatening immune-mediated disease in which the immune system recognizes desmosomal proteins as antigenic; this disrupts desmosomal adhesion, causing spinous-layer acantholysis, intraepithelial blistering and ulceration. Compatible histology and direct immunofluorescence corroborate the diagnosis.
Worked example: Persistent lip and soft-palate ulceration in a woman in her fifties shows intraepithelial acantholysis on histology, and direct immunofluorescence corroborates pemphigus vulgaris rather than simple traumatic ulceration.
Mistake to avoid: Diagnosing pemphigus vulgaris from ulcer appearance alone without compatible microscopic and immunofluorescence findings.
Reference: [11]
16. Erosive lichen planus distribution
Severe erosive oral lichen planus tends to present bilaterally and symmetrically on the buccal mucosa and vestibule, and usually shows some degree of Wickham's striae. These features help place it in an ulcer differential, though lichenoid mucositis remains possible.
Worked example: Symmetrical erosions on both buccal mucosae and vestibules, bordered by fine Wickham's striae, favour erosive lichen planus over an isolated traumatic ulcer, while lichenoid mucositis stays on the differential.
Mistake to avoid: Treating bilateral symmetry and Wickham's striae as definitive proof that no other ulcerative disease is present.
Reference: [11]
17. Multisite ulceration and systemic context
Oral ulceration with ocular, genital or skin findings broadens the differential. Behcet syndrome combines oral ulcers, anogenital ulcers and eye lesions; paraneoplastic pemphigus causes severe mucocutaneous ulceration in association with malignant neoplasms such as lymphoma and with non-malignant conditions—differential clues, not formal criteria.
Worked example: A patient with previously diagnosed lymphoma develops severe oral ulceration with genital ulcers and skin lesions; the clinician includes paraneoplastic pemphigus among systemic possibilities rather than concluding from the oral appearance alone.
Mistake to avoid: Treating the lymphoma association and ulcer distribution as proof of paraneoplastic pemphigus.
Reference: [11]
18. Oral candidiasis and confirmatory microscopy
In adults and adolescents with HIV, oropharyngeal candidiasis typically appears as painless, creamy white plaque-like lesions that, unlike oral hairy leukoplakia, can be scraped off the mucosa. When laboratory confirmation is needed, scrapings examined microscopically with a potassium hydroxide preparation can demonstrate characteristic yeast or hyphal forms. Erythematous candidiasis may occur without white plaques, so not every white lesion is thrush.
Worked example: An adult with HIV presents with creamy white plaques on the buccal mucosa and palate that scrape off with an instrument; because confirmation is needed, a KOH preparation of scrapings is examined microscopically and shows characteristic yeast or hyphal forms, supporting thrush.
Mistake to avoid: Classifying every oral white lesion as candidiasis, or claiming a culture alone proves symptomatic infection.
Reference: [12]
19. Suspected versus confirmed esophageal candidiasis
In people with HIV, esophageal candidiasis should be suspected when there is substernal pain, dysphagia or odynophagia, especially with low CD4 counts, and oral thrush strengthens the suspicion. However, the absence of oral thrush does not rule out esophageal involvement, and symptoms are not specific because other causes of esophagitis remain possible. Definitive diagnosis requires endoscopic visualization with histopathologic demonstration of Candida yeast forms in tissue, confirmed by fungal culture and speciation.
Worked example: A person with HIV and a low CD4 count reports dysphagia and odynophagia but has no oral plaques; esophageal candidiasis is still suspected because absent oral thrush does not rule out esophageal involvement, and definitive diagnosis would require endoscopy with histopathology plus fungal culture and speciation.
Mistake to avoid: Treating a normal oral examination as a rule-out test for esophageal candidiasis in a symptomatic patient with HIV.
Reference: [12]
20. Investigating persistent candidiasis
Under the adult and adolescent HIV guidance, treatment failure is defined as persistence of signs or symptoms of oropharyngeal or esophageal candidiasis within 7 days of appropriate antifungal therapy. Persistence then requires reassessment, including confirmatory culture with drug susceptibilities and, for esophageal disease, endoscopy, to distinguish azole resistance from other causes of esophagitis. The appropriateness of the initial therapy must be assessed, and no replacement drug or dose is specified here.
Worked example: An adult with HIV still has esophageal symptoms seven days after appropriate antifungal therapy; the clinician reassesses whether the initial treatment was appropriate and arranges confirmatory culture with drug susceptibilities, plus endoscopy for esophageal disease, rather than simply repeating the same regimen.
Mistake to avoid: Labeling persistent symptoms as azole resistance without confirmatory culture, susceptibility testing or endoscopic assessment.
Reference: [12]
21. Topical therapy and esophageal involvement
In adults and adolescents with HIV, when esophageal candidiasis is suspected, topical therapy alone is not recommended; systemic antifungals are required for effective esophageal treatment. Pregnancy and significant drug–drug interactions with antiretroviral drugs affect selection, but no specific drug, dose or regimen is specified.
Worked example: An adult with HIV has oral thrush and suspected esophageal involvement; topical oral rinses alone are considered inadequate because effective esophageal treatment requires systemic antifungals, with selection individualized for pregnancy status and drug–drug interactions.
Mistake to avoid: Assuming a topical oral antifungal also provides adequate treatment for suspected esophageal candidiasis.
Reference: [12]
Salivary tumour morphology and behaviour
22. Pleomorphic adenoma architecture
Pleomorphic adenoma's main cellular components are epithelial duct-like structures together with mesenchymal-like tissue, such as myxochondroid matrix. Diagnosis rests on this combined epithelial and mesenchymal-like architecture; the historical passage supports morphology only, not staging or recurrence estimates, and matrix alone is insufficient.
Worked example: A biopsy from a slow-growing palatal nodule shows duct-like epithelial structures embedded in a myxochondroid matrix. The pathologist considers pleomorphic adenoma based on this combined biphasic pattern rather than on matrix alone.
Mistake to avoid: Calling any myxochondroid matrix pleomorphic adenoma without identifying the duct-like epithelial structures.
Reference: [10]
23. Mucoepidermoid carcinoma and grading restraint
Low-grade mucoepidermoid carcinoma is characterized by an abundance of mucous-producing cells and duct-like structures with cystic dilation, but the mere presence of certain cell types and architecture should not be used to determine histologic grade. The passage supplies no complete current grading system, so no numerical grade or treatment can be inferred.
Worked example: A cystic salivary tumour contains many mucous-producing cells with cystically dilated duct-like structures. The pathologist notes these features are compatible with low-grade mucoepidermoid carcinoma but evaluates the remaining histologic features before assigning any grade, rather than grading from one cell population alone.
Mistake to avoid: Assigning low grade to a cystic mucous-cell-rich tumour without assessing the other required grading features.
Reference: [10]
24. Epithelial-myoepithelial carcinoma cell layers
Epithelial-myoepithelial carcinoma is biphasic, with two cell populations arranged in two layers around duct lumina: an inner layer of cuboidal or columnar epithelial cells and an outer layer of cuboidal or columnar cells with pale or clear cytoplasm, consistent with myoepithelial cells. This morphology supports diagnosis, but the passage does not provide a complete immunohistochemical differential, and partial encapsulation does not negate its description of invasion.
Worked example: A salivary gland tumour shows ducts lined by an inner layer of cuboidal epithelial cells and an outer layer of cells with pale, clear cytoplasm. This repeated two-layered ductal pattern supports considering epithelial-myoepithelial carcinoma rather than any other clear-cell tumour.
Mistake to avoid: Diagnosing every clear-cell salivary tumour as epithelial-myoepithelial carcinoma without demonstrating the characteristic two-layered ductal architecture.
Reference: [10]
25. Palatal location and the salivary differential
A posterior or lateral palatal swelling should raise suspicion of a salivary gland neoplasm, because torus palatinus typically occupies the middle or anterior hard palate; location guides the differential, but tissue diagnosis may still be required, and both benign and malignant salivary lesions occur here.
Worked example: A 48-year-old patient presents with a firm, lateral hard-palate swelling; the clinician includes salivary neoplasm in the differential rather than assuming torus palatinus, and arranges tissue assessment.
Mistake to avoid: Labelling a lateral soft-palate swelling a torus palatinus based on palatal location alone.
Reference: [10]
26. Perineural invasion in salivary carcinoma
Perineural invasion (neurotropism) in primary salivary gland carcinoma is an adverse prognosticator and a required data element in the CAP salivary resection protocol; it should be reported even when a tumour appears well differentiated, though prognostic association does not determine any individual patient's outcome.
Worked example: A resection report describes a low-grade-appearing salivary carcinoma with tumour cells identified within a nerve; the pathologist records perineural invasion as a required adverse prognostic element.
Mistake to avoid: Omitting perineural invasion from the report because the carcinoma otherwise looks bland and well differentiated.
Reference: [6]
27. Gross versus microscopic extraparenchymal extension
For major salivary gland carcinoma under AJCC Version 9, extraparenchymal extension requires clinical or macroscopic invasion of soft tissues or nerve, except T4a and T4b structures; microscopic evidence alone does not suffice, and this major-gland criterion does not transfer to minor salivary pT1–3.
Worked example: A parotidectomy specimen shows tumour infiltrating skeletal muscle only on microscopy, with no gross or clinical extension; the tumour is not classified as having extraparenchymal extension for pT3 purposes.
Mistake to avoid: Assigning pT3 for purely microscopic parotid soft-tissue invasion without any gross or clinical extraparenchymal extension.
Reference: [6]
28. Depth of invasion in minor salivary carcinoma
Under AJCC Version 9 in the cited salivary protocol, minor salivary gland carcinomas are categorized by size criteria alone for pT1–3; depth of invasion is not used in their T classification, although this does not replace separate advanced-category invasion criteria.
Worked example: A palatal minor salivary carcinoma measures 1.5 cm with 6 mm invasion; pT1 is assigned on size alone, without applying an oral squamous carcinoma depth-of-invasion table.
Mistake to avoid: Staging a palatal minor salivary carcinoma using the oral squamous carcinoma depth-of-invasion table.
Reference: [6]
29. Intraparotid tumour origin and nodal involvement
In the CAP salivary gland protocol (AJCC Version 9), tumour arising in intranodal parotid tissue is not a metastasis, whereas lymphatic spread into an intraparotid node is positive; intraparotid nodes involved by direct extension are excluded from positive-node counting, but their number should be documented.
Worked example: A parotidectomy shows one intraparotid node with confirmed lymphatic spread and two nodes involved only by direct extension; the report records one positive node and separately notes the two direct-extension nodes.
Mistake to avoid: Reporting every intraparotid tumour focus as nodal metastasis without assessing its origin or spread route.
Reference: [6]
Microscopic classification and biomarker interpretation
30. Neuroendocrine marker expression and tumour identity
Synaptophysin, chromogranin and INSM-1 expression can occur in other tumour types at each head and neck subsite, so a marker result is not a standalone diagnosis; morphology, other immunophenotypic and molecular features supersede neuroendocrine marker expression for classification.
Worked example: A parotid tumour with solid sheets and rhabdoid morphology stains synaptophysin-positive; because morphology and other immunophenotypic findings point elsewhere, the pathologist classifies it by those features rather than as neuroendocrine carcinoma.
Mistake to avoid: Signing out synaptophysin-positive carcinoma as neuroendocrine carcinoma despite morphology and immunophenotype pointing to a different tumour type.
Reference: [6]
31. Head and neck neuroendocrine grading boundaries
In the CAP oral cavity protocol (version 4.3.0.0), Ki-67 is recommended but not required for head and neck neuroendocrine tumours, and the grade 1–2 boundary by proliferation index is not yet established; grade 3 NET remains provisional, with no current supporting evidence.
Worked example: An oral neuroendocrine tumour shows 5 mitoses per two mm2 with necrosis, fitting the grade 2 row; its Ki-67 of 8% is recorded but not used to delineate grade, and grade 3 NET is not assigned.
Mistake to avoid: Grading a head and neck neuroendocrine tumour as grade 3 NET based only on Ki-67.
Reference: [5]
32. p16 staining percentage and intensity
In the CAP biomarker template (version 2.3.0.0), p16 as a surrogate for transcriptionally active high-risk HPV is negative below 50%, equivocal at 50% to under 70%, and positive at 70% or greater moderate-to-strong nuclear and cytoplasmic staining; these are reporting categories, not universal indications.
Worked example: An oral cavity squamous cell carcinoma shows moderate-to-strong nuclear and cytoplasmic p16 staining in 65% of tumour cells; the report records the result as equivocal within these surrogate categories.
Mistake to avoid: Calling p16 staining in 55% of cells positive and inferring transcriptionally active high-risk HPV causation.
Reference: [7]
33. Viral in situ hybridization signal location
In the CAP head and neck biomarker template, EBER ISH positivity is defined as nuclear signal, whereas HPV E6/E7 mRNA ISH may show cytoplasmic and/or nuclear signals, so each viral assay uses its own signal-location criterion.
Worked example: A sinonasal biopsy reported for EBER ISH shows punctate staining confined to tumour cell nuclei, so the pathologist records the assay as positive (nuclear signal) in the template.
Mistake to avoid: Reporting HPV E6/E7 mRNA ISH as positive only when signals are strictly nuclear, mirroring the EBER criterion incorrectly.
Reference: [7]
34. HER2 protein scoring and gene amplification
In the salivary duct carcinoma section of the CAP Head and Neck Biomarker Reporting Template, HER2 IHC score 2+ is recorded as equivocal, and HER2 amplification by in situ hybridization is reported as a separate result. The scoring-system field lists the breast system, the gastric/gastroesophageal junction system (Rüschoff/Hofmann method), or another specified system.
Worked example: A salivary duct carcinoma case is reported with HER2 IHC score 2+ (equivocal) using the breast scoring system, and HER2 ISH separately reported as positive (amplified), each as its own result.
Mistake to avoid: Converting an equivocal HER2 IHC score 2+ directly into a positive amplified ISH result without separate testing.
Reference: [7]
35. Loss-pattern SWI/SNF immunohistochemistry
In the template's SWI/SNF complex deficient sinonasal carcinoma/teratocarcinosarcoma section, loss of nuclear INI1 or BRG1 staining is reported as positive for deletion/alteration, while retained nuclear staining is reported as negative for alteration.
Worked example: A SWI/SNF deficient sinonasal carcinoma case shows complete absence of BRG1 nuclear staining in tumour cells, so the template entry records loss of nuclear staining, positive for alteration.
Mistake to avoid: Recording absent INI1 nuclear staining as negative for alteration because no staining was visualized.
Reference: [7]
36. SDHB staining compartment in paraganglioma
The paraganglioma section of the template evaluates SDHB in the cytoplasmic compartment: retained cytoplasmic staining is negative for deletion/alteration and loss of cytoplasmic staining is positive, unlike the nuclear assessment used for INI1 and BRG1.
Worked example: A paraganglioma specimen shows absent SDHB staining in tumour cell cytoplasm, so the reporting template records loss of cytoplasmic staining, positive for deletion/alteration.
Mistake to avoid: Judging SDHB positivity by loss of nuclear staining, applying the INI1 criterion to a cytoplasmic assay.
Reference: [7]
37. Rearrangement detection and fusion partner reporting
The CAP head and neck biomarker template reports secretory carcinoma findings as detected ETV6 or NTRK rearrangements, with fusion partner specified only if available; detection alone does not establish a named fusion or treatment response.
Worked example: A report records NTRK rearrangement detected, type NTRK3, with the fusion partner field left as cannot be determined, rather than asserting a confirmed ETV6–NTRK3 fusion the assay never demonstrated.
Mistake to avoid: Rewriting an unspecified NTRK3 rearrangement as a confirmed ETV6–NTRK3 fusion and implying therapy response.
Reference: [7]
Oral cancer assessment and staging
38. Choosing the correct oral cancer protocol
The CAP oral cavity protocol covers wet mucosal lip carcinoma, but directs dry vermilion lip carcinomas and salivary gland cancers to other protocols, so protocol choice must follow tumour type and site, not the broad oral cancer label.
Worked example: A resection of a minor salivary gland carcinoma of the palate is reported using the Salivary Gland Cancer protocol, while a wet mucosal lip squamous carcinoma uses this oral cavity protocol.
Mistake to avoid: Selecting the oral cavity protocol for a palatal minor salivary carcinoma based only on the oral cancer label.
Reference: [5]
39. Squamous carcinoma grade and prognostic limits
For conventional squamous cell carcinoma, histologic grading performs poorly as a standalone prognosticator, yet it remains a basic tumour characteristic that should be recorded when applicable, alongside independent assessment of invasion and stage.
Worked example: A well-differentiated (grade 1) oral tongue squamous carcinoma is still reported with its measured depth of invasion and nodal findings, since grade alone does not predict the individual outcome.
Mistake to avoid: Telling the surgeon that grade 1 tumours need no invasion assessment because they always behave favourably.
Reference: [5]
40. Oral carcinoma size and depth of invasion
AJCC 8th Edition oral cavity pT categories combine tumour size with depth of invasion, which is measured as invasion depth and is not tumour thickness; both parameters must be assessed before assigning a pT category.
Worked example: A 1.8 cm floor-of-mouth squamous carcinoma with 7 mm depth of invasion, without separate advanced local invasion, is classified pT2 because DOI exceeds 5 mm despite the size being 2 cm or less.
Mistake to avoid: Assigning pT1 to a 1.8 cm tumour using the 7 mm tumour thickness measurement instead of true depth of invasion.
Reference: [5]
41. Superficial bone erosion versus advanced invasion
Under AJCC 8th Edition oral cavity criteria, superficial erosion of bone or tooth socket by a gingival primary tumour, on its own, does not justify T4 classification. Other size, depth-of-invasion or adjacent-structure findings may independently establish an advanced T category.
Worked example: A gingival squamous cell carcinoma shows superficial socket erosion without cortical invasion or other advanced features, so the lesion is not automatically classified as pT4a.
Mistake to avoid: Classifying a gingival primary as T4a based only on superficial tooth-socket erosion.
Reference: [5]
42. Metastatic deposit size versus lymph node size
For this oral cavity reporting element, measure the cross-sectional diameter of the largest nodal metastatic deposit, not the whole lymph node. Measurement may be made grossly at macroscopic examination or, if necessary, on the histologic slide microscopically.
Worked example: A neck dissection specimen contains a 24 mm lymph node whose largest metastatic deposit measures 9 mm; the reported metastatic deposit size is 9 mm, not the node's outer diameter.
Mistake to avoid: Reporting a 24 mm node's outer diameter as the metastatic deposit measurement.
Reference: [5]
43. Isolated tumour cells and evidence uncertainty
Isolated tumour cells are single cells or small clusters no greater than 0.2 mm in greatest dimension. The generic recommendation classifies such nodes as N0, but the oral protocol cautions that evidence supporting this practice in head and neck squamous cell carcinoma is lacking, so small size does not prove absence of prognostic significance.
Worked example: A histologically examined node contains a 0.15 mm tumour cell cluster, meeting the ITC size definition, yet the report cannot treat this finding as proven prognostically insignificant.
Mistake to avoid: Telling the surgeon that isolated tumour cells are definitively prognostically harmless in head and neck cancer.
Reference: [5]
44. Post-treatment staging descriptors
The y prefix identifies classification performed during or after initial multimodality therapy. The ycTNM or ypTNM records the extent of tumour actually present at that examination, not an estimate of pretreatment extent. Distinguish clinical from pathological classification, and remember a pathology report's categories alone do not establish every component of final stage.
Worked example: After neoadjuvant chemoradiation, a resected tongue primary shows 8 mm residual depth of invasion; the ypT category records this assessed residual tumour rather than reconstructing the untreated extent.
Mistake to avoid: Using post-treatment residual tumour measurements to estimate the original pretreatment T category.
Reference: [5]
45. Extranodal extension versus inflammatory adherence
In the CAP salivary protocol, only definitive ENE is recorded as positive: tumour crossing between adjacent nodal capsules ('matted') is ENE-positive, whereas nodes adherent from inflammation and stromal reaction without tumour transgressing capsules are ENE-negative.
Worked example: Two adjacent nodes look inseparable grossly, but microscopy shows only inflammatory stromal reaction with intact capsules and no tumour crossing, so the report records them as ENE-negative.
Mistake to avoid: Recording difficult-to-separate, inflamed adherent nodes as ENE-positive without microscopic evidence of tumour crossing capsules.
Reference: [6]
Complex medical care and temporomandibular disorders
46. Xerostomia versus salivary hypofunction
Xerostomia is the subjective sensation of oral dryness, while salivary gland hypofunction is the objectively measured reduction in salivary flow; the symptom and the measurement may or may not occur together, so each requires separate assessment.
Worked example: A patient reports persistent oral dryness, but measured unstimulated flow is normal; the clinician documents the symptom and investigates causes rather than dismissing the discordance.
Mistake to avoid: Diagnosing hyposalivation from a dryness complaint alone without any objective salivary flow measurement.
Reference: [13]
47. Salivary flow calculation and collection conditions
Express collected saliva as a rate—volume divided by collection time—and match the threshold to the collection condition: unstimulated flow of 0.1 mL/min or less, or chewing-stimulated flow of 0.7 mL/min or less, indicates reduced flow.
Worked example: An unstimulated collection yields 0.4 mL over five minutes, giving 0.08 mL/min, which is below the 0.1 mL/min unstimulated threshold for hyposalivation.
Mistake to avoid: Comparing a five-minute collected volume directly against the per-minute threshold without dividing by time.
Reference: [13]
48. Dry mouth, dry eyes and Sjögren disease
Dry mouth combined with dry eyes, sometimes accompanied by persistent or recurrent salivary gland swelling, can suggest Sjögren disease, a systemic condition; the cited passage provides no formal classification criteria, so clinical suspicion warrants further investigation rather than diagnosis from dryness alone.
Worked example: A woman reports dry mouth and dry eyes, and her parotid gland has recurrent swelling; the clinician considers Sjögren disease among causes and reviews her medication history.
Mistake to avoid: Diagnosing Sjögren disease from dry mouth alone while overlooking medication-induced xerostomia as an alternative cause.
Reference: [13]
49. Chemotherapy and radiotherapy salivary effects
Cancer chemotherapy generally produces acute oral toxicities that resolve after therapy ends and damaged tissue heals, whereas head and neck radiotherapy can cause acute toxicity plus permanent tissue damage placing patients at lifelong risk; effects depend on the treatment and tissues exposed.
Worked example: A patient reports persistent dry mouth five years after head and neck radiotherapy; this remains clinically relevant even though chemotherapy-associated toxicity generally resolves, because radiation-induced tissue damage can be permanent and carry lifelong risk.
Mistake to avoid: Telling a radiotherapy patient their dry mouth will resolve like chemotherapy-associated toxicity typically does.
Reference: [13]
50. Procedure risk and patient bleeding risk
Bleeding risk assessment weighs both the extent and invasiveness of the planned dental procedure and individual patient factors, including medications, kidney or liver disease, bone marrow disorders, and the patient's own bleeding history, rather than relying on a procedure category alone.
Worked example: Before a biopsy for a patient with kidney disease, the dentist considers the procedure's invasiveness, the renal condition's possible effect on coagulation, and any previous bleeding episodes rather than the procedure's category alone.
Mistake to avoid: Labelling a biopsy higher risk and then skipping questions about the patient's bleeding history.
Reference: [15]
51. Clarifying antithrombotic treatment before intervention
When medication or medical information is unclear, consult the patient's prescribing clinician, who may be a haematologist or cardiologist, in advance of dental treatment to inform bleeding-risk planning, using interim non-invasive measures for pain if required; urgency and referral depend on the individual case.
Worked example: A patient cannot confirm which anticoagulant combination she takes; the dentist contacts her prescribing clinician before the planned procedure, arranging interim non-invasive pain relief meanwhile, rather than guessing the regimen or altering medication independently.
Mistake to avoid: Guessing an uncertain anticoagulant regimen and independently setting an interruption schedule before surgery.
Reference: [15]
52. TMD screening and diagnostic grouping
The 3Q/TMD screener helps clinicians identify TMD but does not diagnose; information from history and examination supports grouping as myogenous, arthrogenous, or combined, after excluding dental, periodontal, mucosal and other relevant mimics, in adults aged at least 18.
Worked example: An adult screens positive on 3Q/TMD; examination reveals tenderness of the masticatory muscles without joint findings, and dental, periodontal and mucosal mimics are excluded, supporting a myogenous grouping rather than a definitive subtype diagnosis.
Mistake to avoid: Recording a positive 3Q/TMD screen as a definitive arthrogenous diagnosis without examination.
Reference: [14]
53. Matching TMD imaging to the clinical question
The adult painful TMD guidance does not advocate routine ionizing TMJ imaging for diagnosing painful TMD; appropriateness is judged case by case. When justified, CBCT or CT better assesses hard-tissue disease such as DJD, while MRI is the only modality that accurately depicts articular disc position. Imaging remains an adjunct to, never a substitute for, thorough clinical examination.
Worked example: A clinician suspecting disc displacement without reduction in an adult with painful TMD requests MRI, because disc position is the clinical question, rather than CBCT; had degenerative hard-tissue change been the question, CBCT covering the condyle, glenoid fossa and articular eminence would be preferred.
Mistake to avoid: Ordering a panoramic radiograph routinely for every painful TMD presentation instead of relying on clinical examination.
Reference: [14]
54. Conservative TMD care and surgical limits
Where surgery is indicated, the adult painful TMD guidance positions it as an adjunct to supported self-management and conservative strategies, never as a sole or first-line option. It also states there remains no evidence that surgical management provides benefit in myogenous TMD, although certain severe arthrogenous or disc-displacement presentations may justify earlier specialist assessment.
Worked example: An adult with myogenous TMD affecting the masticatory muscles continues supported self-management and conservative measures after persistent pain, because the guidance finds no evidence that surgery benefits myogenous TMD; persistent pain alone does not establish surgical benefit.
Mistake to avoid: Referring persistent myogenous TMD for joint surgery solely because conservative care had not resolved the pain.
Reference: [14]
55. Protecting the TMJ during dental care
For patients with known or suspected TMD, dental care should protect the TMJ complex using bite blocks, minimized jaw opening time and gentle joint manipulation when required, with particular attention during sedation or general anaesthesia, where reduced muscle tone and airway manoeuvres add joint stress. This is an individualized planning principle rather than a prescribed technique.
Worked example: Before restoring multiple quadrants under general anaesthesia in an adult with known TMD, the dentist plans bite-block use and shorter, interrupted periods of opening instead of one sustained maximal opening, and discusses supported self-management strategies during consent and after the procedure.
Mistake to avoid: Holding a known TMD patient's mouth maximally open with a prop throughout a lengthy procedure without joint protection.
Reference: [14]
Laboratory assessment and reporting
56. When a tumour-bed margin represents the final margin
Under the CAP oral cavity protocol, whether an additional tumour-bed specimen represents a true final margin is a surgeon-pathologist judgment. Generally supporting features include adequate size and thickness for radial processing, orientation to the new true margin surface, and confirmed correspondence with the main resection.
Worked example: A thick, ink-oriented tumour-bed revision specimen is fitted to the corresponding aspect of the main resection and jointly confirmed by surgeon and pathologist, so it can be considered a true final margin; a small unlabelled fragment from the same bed could not automatically negate an involved main-specimen margin.
Mistake to avoid: Reporting a small unoriented tumour-bed fragment as negative clearance, overriding an involved main-specimen margin.
Reference: [5]
57. Core, conditional and optional reporting elements
Under the cited CAP protocols, core data elements must always be reported, conditional elements only when applicable, and plus-marked optional elements are discretionary; synoptic reporting pairs each data element with its response.
Worked example: A pathologist reporting an oral cavity resection omits an applicable conditional element, treating it as optional; the CAP protocol requires conditional elements whenever applicable, while only plus-marked optional elements may be left unreported.
Mistake to avoid: Treating every template field as mandatory simply because it appears in the case summary.
Reference: [5]
58. Lymph node sampling for extranodal extension
The cited salivary protocol recommends sampling that maximizes the nodal perimeter examined: grossly negative nodes are submitted entirely, positive nodes representatively with peripheral emphasis, and serial sectioning is recommended for nodes above 5 mm.
Worked example: A grossly positive node is sampled with one central section; tumour is confirmed, but the capsule periphery is unexamined, so definitive extranodal extension could be missed despite adequate demonstration of nodal metastasis.
Mistake to avoid: Confirming tumour within a positive node and assuming the capsule boundary is thereby assessed.
Reference: [6]
59. Responsibility for biomarker interpretation and records
The cited biomarker template states that the laboratory performing the testing or providing the interpretation is responsible for completion; synoptic reporting by the tissue-submitting laboratory is also encouraged so results remain accessible in the record.
Worked example: A tissue-submitting laboratory receives MAML2 rearrangement results from a reference laboratory and reports them synoptically, preserving the reference laboratory's assay interpretation while ensuring the result is available in the patient's medical record.
Mistake to avoid: Substituting the submitting laboratory's own assumption for a reference laboratory's biomarker interpretation.
Reference: [7]
60. Salivary nodal classification by count and ENE
AJCC Version 9 salivary N classification uses positive-node count and extranodal extension: 1-3 positive nodes is pN1, and more than 3 or any ENE is pN2; size and laterality no longer apply, after intraparotid exceptions.
Worked example: Four positive nodes without extranodal extension are classified pN2 by count alone under Version 9; older size-and-laterality rules carried over from oral squamous or historical salivary staging do not apply here.
Mistake to avoid: Downgrading four positive nodes to pN1 because each metastatic deposit measured under a centimetre.
Reference: [6]
Sources
- 2027 NDSE Protocol: Combined Oral Medicine and Oral Pathology blueprint, pages 35–36
- Official NDSE specialty: Oral Medicine and/or Oral Pathology
- Official NDSE FAQs: distinction from the separate Fellowship Examination
- Official 2027 NDSE specialty examination dates
- CAP Oral Cavity Cancer Protocol, version 4.3.0.0, April 2026—explanatory notes on histology, invasion, margins and staging
- CAP Salivary Gland Resection Protocol, version 1.0.0.0, April 2026—classification, grading and AJCC version 9 staging
- CAP Head and Neck Biomarker Reporting Template, version 2.3.0.0, April 2026—testing and interpretation guidance
- University of Washington: Brown Tumor of Hyperparathyroidism—explained radiographic, histologic and laboratory differential diagnosis
- University of Washington: Juvenile Ossifying Fibroma—explained differential diagnosis of a mixed jaw lesion
- University of Washington: Epithelial-Myoepithelial Carcinoma—explained salivary neoplasm differential and histopathology
- University of Washington: Pemphigus Vulgaris and Immune-Mediated Oral Ulceration—explained histology and immunofluorescence
- NIH: Mucocutaneous Candidiasis in Adults and Adolescents with HIV—diagnosis, antifungal treatment and monitoring; reviewed March 2026
- ADA: Xerostomia—medication effects, salivary assessment, preventive care and management
- NHS England GIRFT/RCS: Management of Painful Temporomandibular Disorder in Adults, version 1.1, August 2025
- SDCEP: Anticoagulants and Antiplatelet Drugs—medical risk assessment and procedural bleeding management