ENT Flashcards
Granulomatous thyroiditis: Hormonal status.
Initial phase: T4 and T3 often elevated.
Resolution: Usually euthyroid, but can be hypothyroid.
Granulomatous thyroiditis:
A. Age group.
B. Symptoms.
A. Middle-aged women.
B. Thyroidal tenderness, fever, sore throat, malaise.
Granulomatous thyroiditis: Histology (3).
Foreign-body granulomas centered on follicles.
Giant cells with ingested colloid; neutrophils early; mononuclear cells.
Variable fibrosis.
Granulomatous thyroiditis vs. sarcoidosis.
Sarcoidosis: Granulomas are in the interstitium rather than centered on follicles.
Granulomatous thyroiditis vs. fungal thyroiditis.
Fungal thyroiditis: Usually acute inflammation with necrosis; granulomas are less frequent.
Granulomatous thyroiditis vs. Hashimoto’s thyroiditis.
Hashimoto’s thyroiditis:
- Germinal centers.
- Oncocytic change.
Granulomatous thyroiditis vs. palpation thyroiditis.
Palpation thyroiditis:
- Fewer giant cells and mononuclear cells within thyroid follicles.
- No neutrophils.
Hashimoto’s thyroiditis:
A. Geography.
B. Associated HLA types.
A. Areas with abundant iodine.
B. DR3, DR5.
Hashimoto’s thyroiditis: Associated genetic diseases (3).
Turner’s syndrome.
Down’s syndrome.
Familial Alzheimer’s disease.
Hashimoto’s thyroiditis: Pitfalls in diagnosis (2).
Parasitic nodules may be confused with nodal metastases.
Optically clear nuclei may be overdiagnosed as papillary thyroid carcinoma.
Hashimoto’s thyroiditis: Lymphocytes.
Mixture of B and T cells.
Hashimoto’s thyroiditis vs. nonspecific lymphocytic thyroiditis (3).
Nonspecific lymphocytic thyroiditis:
− Fewer germinal centers.
− No oncocytic change.
− Minimal fibrosis.
Riedel’s thyroiditis:
A. Age group.
B. Associated fibrosing disorders (3).
A. Peak in the fifth decade.
B. Mediastinal fibrosis; retroperitoneal fibrosis; sclerosing cholangitis.
Riedel’s thyroiditis: Inflammation.
Lymphocytes, plasma cells, neutrophils, histiocytes, eosinophils.
No giant cells, no germinal centers.
Riedel’s thyroiditis: Vascular change.
“Occlusive phlebitis”: Lymphocytes and plasma cells cause thickened wall and myxoid change.
Riedel’s thyroiditis vs. undifferentiated thyroid carcinoma.
The carcinoma contains scattered malignant cells; IHC may help.
Riedel’s thyroiditis:
A. Treatment.
B. Outcome.
A. Corticosteroids or tamoxifen; surgery as needed.
B. Hypothyroidism in half of cases.
Graves’ disease: Associated HLA types.
DR3, B8.
Histology of Graves’ disease:
A. Untreated.
B. After treatment with radioactive iodine.
A. Hyperplastic thyroid follicles with decreased colloid; variable lymphocytic inflammation.
B. Nuclear atypia, stromal fibrosis, more colloid.
Amyloid goiter:
A. Location of amyloid.
B. Other histologic features (2).
A. Around vessels and between thyroid follicles.
B. Squamous metaplasia, secondary atrophy of follicles.
Dyshormogenetic goiter: Most common functional defect.
Inability to incorporate iodine.
Dyshormogenetic goiter: Most commonly associated malignancy.
Follicular carcinoma.
Dyshormogenetic goiter: Gross appearance.
Enlarged, nodular thyroid gland.
Dyshormogenetic goiter: Histologic architecture (2).
Small follicles contain scant colloid and form clusters that are separated from one another by fibrous bands.
Follicular cells may form papillae.
Dyshormogenetic goiter: Cytology.
Often hypercellular and pleomorphic.
Thyroglossal-duct cyst:
A. Lining epithelium.
B. Stroma.
A. Respiratory or squamous.
B. Mucus glands and thyroid follicles.
Thyroglossal-duct cyst: Most commonly associated malignancy.
Papillary thyroid carcinoma.
Causes of finding of ciliated cells on FNA of the thyroid gland (2).
Thyroglossal-duct cyst.
Tracheal aspirate.
Branchial-cleft cyst:
A. Anatomic site.
B. Origins (4).
A. Anterolateral neck.
B. 1st, 2nd, 3rd, or 4th branchial pouch.
Branchial-cleft cyst: Age group.
Children and young adults.
Unusual in older adults.
Branchial-cleft cyst: Lining epithelium.
Squamous, columnar, or ciliated.
Lining may contain mucinous, serous, or sebaceous glands.
Branchial-cleft cyst:
A. Stroma.
B. Contents.
A. Lymphoid.
B. Anucleate squames, histiocytes, or cholesterol clefts.
Nodal metastasis of SCC mimicking a branchial-cleft cyst: Most common sites of primary tumor.
Tonsils, base of tongue.
Nodal metastasis of PTC mimicking a branchial-cleft cyst: Recognition (4).
Nuclear features of papillary thyroid carcinoma.
IHC for TTF-1, thyroglobulin.
Presence of thyroglobulin in FNA fluid.
Presence of thyroid tissue in the lateral neck implies metastasis.
Teratoma of the thyroid gland:
A. Basic types (3).
B. How grade is assigned.
A. Benign (mature), immature, malignant.
B. Based on the maturation of the neural component.
Teratoma of the thyroid gland: Relevance of age to likelihood of malignancy (2).
Infants: >90% are benign.
Adolescents and adults: Half are malignant.
Hyalinizing trabecular tumor: Histologic architecture.
Trabeculae and insulae of cells separated by hyaline bands.
Hyalinizing trabecular tumor: Cytology (3).
Large, elongated cells.
Oval nuclei with nuclear grooves and INCIs.
Halo may surround nucleus.
Hyalinizing trabecular tumor: Genetics.
Some tumors exhibit rearrangements of RET/PTC gene.
Hyalinizing trabecular tumor vs. papillary thyroid carcinoma.
Papillary thyroid carcinoma shows invasive growth.
? Anything else ?
Hyalinizing trabecular tumor vs. medullary thyroid carcinoma (2).
Medullary thyroid carcinoma:
- Amyloid may be present.
- Negative for thyroglobulin.
Follicular adenoma: Associations (2).
Iodine deficiency.
Cowden’s syndrome.
Follicular adenoma:
A. Thickness of capsule.
B. Variant that is most prone to infarction after FNA.
A. Thinner than that of follicular carcinoma.
B. Oncocytic variant.
Follicular adenoma: Histology of toxic variant.
Mimics that of Graves’ disease.
Atypical adenoma: Synonym.
Follicular lesion of uncertain malignant potential.
Atypical adenoma: Histology (4).
May show necrosis or mitotic activity.
Thickened capsule with partial invasion.
Follicular adenoma: Genetics (3).
Aneuploidy (one fourth of cases).
Mutations in RAS.
Rearrangements of PAX8 with PPARγ.
Follicular carcinoma: Association.
Iodine deficiency.
Follicular carcinoma: Histology of capsular invasion (2).
The tumor must fully penetrate the capsule and not merely be present within the capsule.
Hemorrhage and reactive changes suggest FNA artifact.
Follicular carcinoma: Histology of vascular invasion (3).
Vessels must be within or outside the capsule.
There must be at least focal attachment of the tumor to the lining of the vessel.
Some require endothelium on the tumor focus or fibrin deposition.
Follicular carcinoma: Genetics (2).
Some cases show
− t(2;3) :: PAX8−PPARγ.
− Mutations of KRAS, NRAS, or HRAS.
Follicular carcinoma: Metastasis.
Hematogenous, most often to lung and bone.
WHAFFT.
Worrisome histologic alterations following FNA of thyroid.
Papillary thyroid carcinoma: Nuclear features that are essential to diagnosis (3).
Hypochromasia.
Grooves.
Pseudoinclusions.
Metastasis of papillary thyroid carcinoma to regional lymph nodes:
A. Incidence.
B. Effect on prognosis.
A. Occurs in about half of cases.
B. Does not affect long-term prognosis.
Papillary thyroid carcinoma: Appearance of metastasis to lymph node.
Tumor cells may appear flattened.
Papillary thyroid microcarcinoma:
A. Frequent location.
B. Frequent histology.
A. Subcapsular.
B. Scar-like.
Papillary thyroid carcinoma, diffuse sclerosing variant: Location.
Often diffusely involves both lobes of the gland.
Papillary thyroid carcinoma, diffuse sclerosing variant: Histology (4).
Extensive fibrosis.
Squamous metaplasia.
Psammoma bodies.
Lymphocytic infiltrate.
Papillary thyroid carcinoma, diffuse sclerosing variant: Behavior.
Often metastasizes to cervical lymph nodes and to lungs, due to increased lymphovascular invasion.
Papillary thyroid carcinoma, oncocytic variant: Histology (3).
Cells resemble Hürthle cells but have nuclear features of classic PTC.
Nuclear overlap may be absent due to abundance of cytoplasm.
Lymphoid stroma may be present.
Papillary thyroid carcinoma, tall-cell variant: Histology.
Cells are three times as tall as they are wide and have basal nuclei.
Papillary thyroid carcinoma, columnar-cell variant: Histology (3).
Cells contain basal cytoplasmic vacuoles and show squamous metaplasia.
Nuclei are pseudostratified and luminal.
Papillary thyroid carcinoma, tall-cell and columnar variants: Shared morphology (3).
Often . . .
− Large.
− Extend beyond thyroid gland.
− Invade vessels.
Papillary thyroid carcinoma: Genetics.
Point mutation in exon 15 of BRAF.
Rearrangements of RET with many other genes.
Rearrangements of TRK with many other genes.
Papillary thyroid carcinoma: Relevance of genetics to histology.
Mutations of NRAS are seen in the follicular variant.
Papillary thyroid carcinoma: Relevance of genetics to therapy.
Tumors with mutations in BRAF and/or RET may respond to inhibitors of tyrosine kinases.
Medullary thyroid carcinoma: Relative frequency of sporadic and hereditary cases.
Sporadic: 80%.
Hereditary: 20%.
Medullary thyroid carcinoma: Incidence of nodal metastasis at presentation.
About 50%.
Medullary thyroid carcinoma: Tumor markers.
Calcitonin: Postoperative monitoring.
CEA: Usually elevated only in late, progressive disease.
Medullary thyroid carcinoma: Diseases associated with hereditary tumors (3).
Familial medullary thyroid carcinoma: No other endocrine abnormalities.
MEN IIA and MEN IIB.
MEN IIA and MEN IIB: Tumors.
Medullary thyroid carcinoma: Often multiple.
Pheochromocytoma; parathyroid adenoma or hyperplasia.
MEN IIB: Mucosal and ocular ganglioneuromas also.
Medullary thyroid carcinoma: Hereditary type with the best prognosis.
Familial medullary thyroid carcinoma (non-MEN).
Medullary thyroid carcinoma: Location in the thyroid gland.
Upper and middle third of lobes.
Medullary thyroid carcinoma: Shapes of tumor cells.
Round, polygonal, spindled, plasmacytoid.
Medullary thyroid carcinoma: Nuclear features (3).
Pseudoinclusions or grooves.
“Salt-and-pepper” chromatin.
Binucleation is common.
Medullary thyroid carcinoma: Stromal contents (3).
Amyloid in 80% of cases; may induce foreign-body reaction.
Calcifications.
Psammoma bodies (rare).
Medullary thyroid carcinoma: Histologic features suggesting germline mutation (2).
Bilaterality.
Presence of C-cell hyperplasia.
Medullary thyroid carcinoma: Immunohistochemistry (4,1,1).
Positive: Calcitonin, synaptophysin, chromogranin, CEA.
Usually positive: TTF-1.
Negative: Thyroglobulin.
Medullary thyroid carcinoma: Genetics (2).
Hereditary cases: Germline mutation in RET.
Sporadic cases: 20-80% have mutated RET.
Medullary thyroid carcinoma vs. reactive hyperplasia of C cells.
Reactive hyperplasia:
- Fewer C cells.
- No fibrosis.
Nodular hyperplasia of C cells: Histology.
Nodules contain >50 C cells.
No fibrosis, no infiltration.
Identified on H and E stain and confirmed by IHC.
Poorly differentiated thyroid carcinoma:
A. Former name.
B. Cell of origin.
A. Insular carcinoma.
B. The follicular cell; may arise from follicular carcinoma or papillary thyroid carcinoma.
Poorly differentiated thyroid carcinoma: Gross pathology (2).
Usually large (>5 cm) and invasive of soft tissues.
Poorly differentiated thyroid carcinoma: Histology (2).
Nests (insulae) of cells with high N:C ratio.
May show convoluted nuclei, necrosis, or mitotic activity (>3 per 10 hpf).
Poorly differentiated thyroid carcinoma: Immunohistochemistry (2,2,1).
Positive: PAX8, cytokeratin.
Variable: Thyroglobulin, TTF-1.
Negative: Calcitonin.
Carcinoma showing thymus-like elements:
A. Age group.
B. Prognosis.
A. Fifth decade.
B. Metastasis in one third of cases.
Carcinoma showing thymus-like elements:
A. Histology.
B. Immunohistochemistry.
A. Moderately pleomorphic cells form sheets and nests with dense fibrosis.
B. Positive for CD5; negative for TTF-1, thyroglobulin, calcitonin.
Spindle-cell tumor with thymus-like elements: Age group.
Second and third decades.
Spindle-cell tumor with thymus-like elements:
A. Histology.
B. Immunohistochemistry.
A. Well-circumscribed biphasic tumor of spindled and epithelial cells forming glands, tubules, and sheets.
B. Negative: TTF-1, thyroglobulin, calcitonin.
Undifferentiated thyroid carcinoma:
A. Synonyms (2).
B. Cell of origin.
C. Prognosis.
A. Anaplastic carcinoma, pleomorphic carcinoma.
B. Follicular cell; most tumors arise from a preexisting thyroid carcinoma.
C. Death in 6 months.
Undifferentiated thyroid carcinoma: Histologic patterns (3).
Squamoid.
Spindle-cell.
Giant-cell.
Undifferentiated thyroid carcinoma: Histology of squamoid pattern.
Resembles non-keratinizing SCC, albeit rarely with squamous pearls.
Undifferentiated thyroid carcinoma: Histology of spindle-cell pattern (2).
Resembles a sarcoma.
Most likely of the three patterns to contain heterologous elements.
Undifferentiated thyroid carcinoma: Histology of giant-cell pattern.
Highly pleomorphic (anaplastic); usually solid growth.
Undifferentiated thyroid carcinoma: Immunohistochemistry.
Positive: Cytokeratin, EMA, vimentin.
Variable: Thyroglobulin, TTF-1.
Undifferentiated thyroid carcinoma: Genetics.
Strong association with mutations in TP53.
Undifferentiated thyroid carcinoma: Important items in the differential diagnosis (4).
Medullary carcinoma: Calcitonin, amyloid.
Sarcoma: Cytokeratin negative.
Lymphoma: CD45 positive.
Metastatic carcinoma.
Thyroid lymphoma: Most common type overall.
Diffuse large B-cell lymphoma.
Thyroid lymphoma: Most common Hodgkin’s type.
Nodular sclerosis.
Thyroid lymphoma vs. thyroiditis and Graves’ disease (3).
Thyroid lymphoma:
− Atypical lymphoid cells.
− Expansion or effacement of germinal centers.
− Neoplastic lymphocytes infiltrate thyroid follicles.
Thyroid lymphoma: Putative origin of plasmacytoma.
MALT lymphoma with plasmacytic differentiation.
Metastases to the thyroid gland: Most common origins (6).
Melanoma.
Breast.
Lung.
Kidney.
Gastrointestinal tract.
Head and neck (mostly SCC).
Parathyroid cyst: Function.
Only a minority cause hyperparathyroidism.
Histology of parathyroid cyst:
A. Lining.
B. Wall.
A. Cells are flat or cuboidal and have basal nuclei and clear cytoplasm.
B. Fibrous.
Parathyroid cyst: Origin.
Some arise from degenerated adenoma or area of hyperplasia.
Parathyroid cyst: Ancillary studies (2).
PTH is positive by IHC and in cyst fluid.
Parathyroid cyst vs. cyst of the 3rd pharyngeal pouch.
Cyst of the 3rd pharyngeal pouch contains both parathyroid and thymic tissue.
Parathyroid hyperplasia:
A. Number of enlarged glands.
B. Relationship to hyperparathyroidism.
A. More than one; usually all 4.
B. Causes about 15% of cases of hyperparathyroidism.
Chemical findings in hyperparathyroidism:
A. Primary.
B. Secondary.
A. High calcium and low phosphate; high PTH.
B. Low calcium and high phosphate (due to renal failure); high PTH.
Parathyroid hyperplasia in MEN syndromes:
A. Which syndromes?
B. Which cells?
A. MEN I, MEN IIA, and MEN IIB.
B. Chief cells.
Parathyroid hyperplasia: Normal weight of parathyroid gland.
Up to 40 mg.
Histology of parathyroid hyperplasia:
A. Cells.
B. Growth patterns.
C. Stroma.
A. Chief cells, oncocytic cells, transitional cells, clear cells, or mixed.
B. Solid, glandlike, or in cords.
C. Decreased fat (decreased within cells also).
MEN syndromes: Genes and their locations.
MEN I: Gene for menin on 11q.
MEN IIA and IIB: RET on 10q.
Parathyroid hyperplasia vs. parathyroid adenoma (2).
Parathyroid adenoma:
− More likely when only one gland is enlarged.
− Rim of compressed normal parathyroid tissue.
Parathyroid hyperplasia: Treatment.
Excision of 3½ parathyroid glands.
Parathyroid adenoma:
A. Cell of origin.
B. Atypical anatomic sites (3).
A. The chief cell.
B. Intrathyroidal, mediastinal, retroesophageal.
Parathyroid adenoma: Relationship to hyperparathyroidism.
Accounts for about 80% of cases of hyperparathyroidism.
Parathyroid adenoma: Inherited syndromes.
MEN I, MEN IIA, MEN IIB.
Hyperparathyroidism−jaw tumor syndrome.
Parathyroid adenoma: Typical weight.
More than 300 mg.
Parathyroid adenoma:
A. Mitotic rate.
B. Growth patterns (4).
A. Usually absent; never high.
B. Solid, nested, glandlike, or pseudopapillary.
Parathyroid adenoma: Contents of cystic structures.
PAS-positive fluid.
Parathyroid adenoma: Features of atypical adenoma (2).
Thickened capsule.
Thick fibrous bands.
No invasion of vessels or of adjacent structures.
Hyperparathyroidism−jaw tumor syndrome.
A. Gene, location, product.
B. Histology of parathyroid adenoma.
A. HRPT2, 1q25, parafibromin.
B. Often cystic.
Parathyroid adenoma: IHC.
Positive: Cytokeratin, PTH, chromogranin.
Parathyroid adenoma: Genetics (2).
Loss of 11q.
Rearrangement of cyclin D1 (PRAD1).
Parathyroid adenoma: Age-related possible mimic.
Oncocytic nodule.
Parathyroid carcinoma:
A. Age group.
B. Degree of hypercalcemia.
A. 45-55 years: 10 years younger than for adenoma.
B. Usually marked: Higher than for adenoma.
Parathyroid carcinoma: Mean weight.
6 grams.
Parathyroid carcinoma: Intraoperative appearance (2).
Invades adjacent structures.
Usually no nodal disease.
Histology of parathyroid carcinoma:
A. Cells (2).
B. Other possible features (3).
A. Usually show only mild or moderate pleomorphism; only 50% show mitotic activity.
B. Thicker capsule than in adenoma, thick fibrous bands, necrosis.
Histology of parathyroid carcinoma: Findings diagnostic of malignancy (2).
Extension into adjacent structures.
Vascular invasion.
Histology of parathyroid carcinoma: Definition of vascular invasion.
Tumor cells are attached to the inside of a vessel located outside the main mass.
Parathyroid carcinoma: Genetics (2).
Loss of 13q (region of RB and BRCA2).
Mutation of HRPT2.
Parathyroid carcinoma: Immunohistochemistry (2).
Positive: Cytokeratin, chromogranin.
Loss of parafibromin may indicate mutation in HRPT2.
Parathyroid carcinoma: Metastasis (3).
To cervical lymph nodes, lung, liver, typically occurring late.
Metastases to the parathyroid glands: Most common origins (5).
Breast.
Skin.
Lung.
Soft tissue.
Leukemia.
Infectious sialadenitis: Causes.
Viruses.
Gram-positive cocci.
Gram-negative bacteria.
Chronic sialadenitis: Rheumatological association.
Rheumatoid arthritis.
Necrotizing sialometaplasia: Histology (3).
Coagulative necrosis of acini.
Squamous metaplasia.
Pseudoepitheliomatous hyperplasia of overlying mucosa.
Necrotizing sialometaplasia: Site.
Any site; palate is the most common.
Benign lymphoepithelial lesion: Histology (3).
Epimyoepithelial islands.
Background lymphoid infiltrate.
Intercellular hyaline matter.
Lymphocytes in benign lymphoepithelial lesion:
A. In the epimyoepithelial islands.
B. In the background.
A. Monocytoid B cells.
B. Mainly T cells.
Benign lymphoepithelial lesion vs. lymphoma (3).
Lymphoma:
− Large aggregates of monocytoid B cells.
− Extension into adjacent fat and connective tissue.
− Monoclonality by IHC.
Lymphoepithelial cyst: Sites and origins (2).
Parotid gland: Remnant of branchial apparatus.
Lymph node: Cystic formation in nests of intranodal salivary-gland tissue.
Lymphoepithelial cyst: Infectious association.
HIV: Cysts are often bilateral.
Histology of lymphoepithelial cyst: Typical (3).
Multilocular.
Glandular and squamous lining.
Hyperplastic lymphoid follicles with germinal centers.
Histology of lymphoepithelial cyst: HIV infection.
Multifocal.
Florid lymphoid hyperplasia.
Salivary-duct cyst:
A. Site.
B. Etiology.
A. Mainly parotid gland.
B. Ductal obstruction.
Salivary-duct cyst: Histology (3).
Squamous lining.
Densely fibrous wall.
Surrounding inflammation and parenchymal atrophy.
Mucocele vs. mucus-retention cyst.
A. Mucocele: Younger patients; extravasation of salivary fluid; no epithelial lining.
B. Mucus-retention cyst: Any age; type of salivary-duct cyst; epithelial lining.
Most common benign tumor of salivary origin.
Pleomorphic adenoma.
Most common tumor of salivary glands in children.
Pleomorphic adenoma.
Pleomorphic adenoma: Most common sites (4).
Parotid gland.
Palate.
Upper lip.
Buccal mucosa.
Pleomorphic adenoma: Most common associated tumor.
Warthin’s tumor.
Pleomorphic adenoma: Effect on facial nerve.
May compress it (resulting in facial paralysis), but does not invade it.
Pleomorphic adenoma: Capsule.
Usually present, but less often in
− Tumors of minor salivary glands.
− Tumors of the myxoid type.
Pleomorphic adenoma: Possible features of the mesenchymal component (4).
Myxoid, hyaline, cartilaginous, or osseous differentiation.
Pleomorphic adenoma: Main variants (2).
Cellular: Mostly epithelial.
Myxoid: Mostly myxochondromatous.
Pleomorphic adenoma: Genetics (2).
Clonal chromosomal rearrangements of
− 8q12.
− 12q13-15.
Pleomorphic adenoma vs. polymorphous low-grade adenocarcinoma (3).
Polymorphous low-grade adenocarcinoma:
− Perineural growth.
− Infiltration of adjacent tissues.
− Tubules or cords of cells at the periphery.
Myoepithelioma: Variants (3).
Spindle-cell.
Plasmacytoid.
Epithelioid.
Myoepithelioma, spindle-cell variant: Histology (2).
Interlacing fascicles of uniform, elongated spindle cells.
Minimal, myxoid stroma.
Myoepithelioma, plasmacytoid variant: Histology.
Cells are plasmacytoid.
Most common variant.
Myoepithelioma, epithelioid variant: Histology (3).
Epithelioid cells with round to oval vesicular nuclei and inconspicuous nucleoli.
Occasional microcystic areas.
Myxoid or hyaline stroma.
Myoepithelioma vs. myoepithelial carcinoma (3).
Myoepithelial carcinoma:
− Infiltrative borders.
− Cellular pleomorphism.
− Possible perineural or vascular invasion.
Myoepithelioma: Type that may be confused with metastatic renal-cell carcinoma.
Clear-cell myoepithelioma lacks the prominent vascular of RCC.
Second most common benign tumor of the salivary glands.
Warthin’s tumor.
Warthin’s tumor: Gross pathology.
Finely nodular and papillary surface.
Brown, turbid fluid in cystic spaces.
Warthin’s tumor vs. oncocytoma.
Oncocytoma:
− Usually solid.
− No lymphoid component.
Warthin’s tumor: Atypical site.
Within an intra-parotid lymph node.
Warthin’s tumor: Associated tumors (2).
Rare association with
− Mucoepidermoid carcinoma.
− Oncocytic carcinoma.
Oncocytoma:
A. Gross pathology.
B. Nucleus.
A. Red-brown tumor with a central scar.
B. Contains large nucleolus.
Oncocytoma: Histologic variations (2).
Clear cells.
Cystic areas.
Oncocytoma: Electron microscopy.
Many mitochondria.
Oncocytoma: Special stain.
PAS highlights cellular glycogen.