Missed Questions: Cytopathology Flashcards
36yo M w/ right sided neck mass. What are the two most common chromosomal abnormalities and the implicated genes in this entity?
(Pleomorphic Adenoma)
- 8q12 rearrangements:
- Most Common: t(3;8) translocation
- Results in CTNNB1-PLAG1 fusion gene
- PLAG1 also often overexpressed in non-t(3;8) translocation
- Most Common: t(3;8) translocation
- 12q15 rearrangements:
- t(3;12), ins(9;12) and t(1;12) translocations
- Gene: HMGA2
65 year old female with irregular, ill-defined facial skin lesion and pleural masses on imaging. EBUS performed.
What are the three most important stains for this entity?
(Malignant Melanoma)
- S-100 +ve.
- Negative staining pretty much excludes the diagnosis.
- HMB-45 +ve – especially deep, often patchy.
- Melan A (MART-1) +ve.
(SOX10 is also + and widely considered the most specific stain)
60 year old male with widely metastatic lesions and elevated AFP. The following is seen in peritoneal washings. Arginase-1 positive on cell block.
What is the diagnosis?
Hepatocellular Carcinoma
(endothelial wrapping shown in reverse image)
- Well-differentiated carcinomas resemble hepatocytes but with larger nuclei, macronucleoli, bile ducts absent
- Poorly differentiated carcinomas show no resemblance to hepatocytes
- Numerous dyshesive, bare nuclei in background
- Thick, disordered plates or balls of neoplastic cells, focally lined by sinusoidal endothelial cells (endothelial wrapping)
- Large tissue fragments traversed by blood vessels (transgressing vessels)
- May show presence of bile, Mallory-Denk bodies, hyaline inclusions, or fat in cytoplasm
- Fibrolamellar variant has neoplastic cells that are larger with oncocytic cytoplasm
- Background fragments of fibrous stroma may be seen
Peritoneal washing. Diagnosis?
Benign Mesothelial Cells
45 year old female with a history of HSIL.
Radiation Changes
- Cytomegaly and karyomegaly with normal N:C ratios
- Degenerative changes in nuclei and cytoplasm with smudging and vacuolization (white arrow)
- Variation in nuclear size and shape with bi- and multinucleation
- Single or multiple nucleoli with coexisting repair
- Polychromatic staining of cytoplasm
34 year old female with small, simple thyroid cyst. FNA performed.
What category, based on the Bethesda System for Reporting Thyroid Cytology, should be assigned?
Nondiagnostic or unsatisfactory (ND/Usat)
(Acellular specimen)
- Cyst fluid only
- Cyst fluid ± histiocytes but lacking 6 groups with 10 cells or thick colloid
- Risk of malignancy is very low if simple cyst, < 3 cm, and in proper clinical setting (ultrasound evidence)
- Since pathologist may not know clinical scenario, there is small chance of intracystic papillary carcinoma
- Hence, best to report as nondiagnostic, cystic contents only
- Virtually acellular specimen (shown in reverse pic)
- Specimen with < 6 groups with 10 cells
- Other
- Material not representative of thyroid (e.g., muscle or trachea)
- Specimen obscured by blood, artifact, ultrasound gel, or poor fixation/staining, which makes accurate interpretation difficult
60 year old male with flank pain and hematuria. Well circumscribed, 4cm right renal pole mass noted on imaging. FNA performed.
Diagnosis?
Renal Oncocytoma
- Cytopathology
- Hypercellular aspirate with granular background
- Loosely cohesive clusters and isolated cells with distinct cytoplasmic membranes
- Abundant granular cytoplasm and uniform round nuclei
- Absent or scant mitoses
- Cell block: Rounded nests of uniform eosinophilic cells
- Macroscopic
- Circumscribed mahogany brown mass (mean: 4.4 cm) with central stellate scar
- Microscopic
- Nests of uniform cells with eosinophilic, granular cytoplasm and loose reticular stroma
- Ancillary Tests
- Immunohistochemistry: AE1/AE3(+), pax-8(+), CD117(+), DOG1(+), vimentin (-), RCC(-), cyclin-D1(-), CK7 [usually(-)]
- Electron microscopy: Cytoplasm packed with mitochondria
75 year old male presents with abdominal pain, weight loss and hyperbilirubinemia.
Mass noted on imaging. FNA performed.
Pancreatic Ductal Adenocarcinoma
- Cytopathology
- “Drunken honeycombs” with irregular spacing and overlap of nuclei
- “Tombstone” isolated malignant cells
- Nuclear enlargement with marked size variation (≥ 4:1 within same cell group)
- Nuclear contour irregularities and irregular chromatin distribution
- Cytoplasmic mucin
- Ancillary Tests
- Positive: CK7, CK8/18/CAM5.2, CK19, CK20 (33%), MUC5AC, mesothelin, S100P, pVHL, IMP-3, maspin
- Negative: MUC2, chromogranin/synaptophysin, trypsin/chymotrypsin
- Mutations in KRAS (~ 90%), CDKN2A (> 95%), TP53 (~ 60%), SMAD4(deletion in ~ 50%)
40 year old female with HPV+ history. Screening pap performed.
High Grade Squamous Intraepithelial Lesion (HSIL)
- Cytopathology:
- Often single cells, may be in clusters.
- Blue cells - nucleus and cytoplasm.
- Increased NC ratio - key feature.
- Irregular nuclear border.
- Chromatin clumping.
- Note:
- Nucleoli uncommon - should prompt consideration of squamous carcinoma.
- DDx:
- LSIL.
- ASC-H.
- Squamous carcinoma.
What are the three (3) cytology “re-examination requirements” set forth by CLIA?
- Prospective re-screening of 10% of negative pap cases (“10% re-screen”)
- Retrospective review of all negative paps from women with a newly diagnosed high-grade squamous intrapithelial lesion (HSIL) (“5-year lookback”)
- Review of discrepancies between pap and biopsy results
Findings from an FNA of a parotid mass in a 45 year old female. PAS+.
What is the genetic alteration associated with this entity?
t(12;15)(p13;q25)
Causing ETV6/NTRK3 fusion gene
(Mammary Analogue Secretory Carcinoma)
- Features:
- Large cells with abundant cytoplasm.
- Small nuclei.
- +/-Lymphocytic infiltrate.
- Solid and microcystic growth pattern.
- +/-Cystic changes lined by hobnail cells - useful feature.
- Stains:
- PAS+
- Mammoglobin +
- S-100 +
FNA of a central lung mass shown below with pap stain and cellblock.
What three (3) immunohistochemical markers will likely be positive?
Synaptophysin (most sensitive), Chromogranin A (most specific) and CD56
(Small Cell Carcinoma of the Lung)
Of the following genetic alterations, which are most common/important in (each of) Adenocarcinoma and Squamous Cell Carcinoma of the lung, respectively?
- EGFR
- ALK
- CDKN2A
- TP53
- PD-1/PDL-1
-
Adenocarcinoma:
- EGFR (Epidermal Growth Factor Receptor): targeted therapy (Erlotinib and Osimertinib)
- ALK (Anaplastic Lymphoma Kinase): targeted therapy (Crizotinib and Ceritinib)
-
Squamous Cell Carcinoma:
- TP53: almost universally mutated.
- CDKN2A (Cyclin Dependant Kinase N2A): mutated in approx. 75% of SqCC. Codes for p16.
- PD-1/PDL-1 (Programmed Death Receptor and Ligand): targeted therapy (Nivolumab and Pembroluzimab).
What are the grading classifications of Pancreatic Neuroendocrine Tumors (PanNET) and how are they divided?
-
Graded by proliferation rate. Limited to well-differentiated pancreatic endocrine tumors; if poorly differentiated, called neuroendocrine carcinoma (rare)
- Well differentiated: Subdivided into low grade (G1), intermediate grade (G2) and high grade (G3).
- G1: < 2 mitoses per 10 HPF or < 3% Ki-67 index
- G2: 2-20 mitoses per 10 HPF or 3-20% Ki-67 index
- G3: >20 mitoses per 10 HPF or >20% Ki-67 index
- Well differentiated: Subdivided into low grade (G1), intermediate grade (G2) and high grade (G3).
Pap smear. Diagnosis?
Low Grade Squamous Intraepithelial Lesion (LSIL)
- General
- Usually regress, i.e. will disappear on their own.
- Low inter-rater concordance.
- Cytopathology Features:
- Nuclei 3x size of intermediate cell - key feature. †
- Irregular nuclear border.
- +/-Perinuclear ‘cavity’ (clearing).
- The best perinuclear halos have a sharp punched-out edge.
- Chromatin clumping/irregular & granular.
- Note:
- † Nucleus diameter ~21-24 μm.
- In the context of exams: 2 of criteria 1-3 is enough to call LSIL.
The following is seen in a conventional prep pap smear of a 50 year old woman.
Diagnosis and reporting?
Benign endometrial cells in a woman >45 years of age (reportable).
Pap smear in 25 year old female. Diagnosis?
Trichomoniasis (Trichomonas vaginalis)
- Low power: grey blob with a nucleus, may be pear-shaped:
- Size: approximately 30 micrometres.
- Shape: usually oval, may have teardrop-shaped.
- Flagellum - hair-thin locomotive stucture, usu. barely visible at 200X - diagnostic feature.
- Cytopathological associations:
- Acute inflammation (neutrophils), often marked - key feature at low power.
- Reactive squamous cells with:
- Nucleoli,
- Perinuclear halos, and
- Moth-eaten cytoplasm; cytoplasm that has multiple vacuoles with star-like spaces.
- Notes:
- Trichomonas is tricky - it is easy to miss if one is not suspicious, in the context of inflammation.
- May vaguely resemble a neutrophil:
- Flagellum useful to differentiate.
- Neutrophil has multiple lobulations of the nucleus.
- May be seen in association of Leptothrix.
- Appearance: long, hair-like.
- Size: ~0.5 x 20 micrometres.
Pleural fluid. Diagnosis?
Adenocarcinoma of the Lung
- Nucleolus.
- Good ones are visible with 10X objective (excludes SCLC).
- Look for subtle large ones - at higher power.
- Neuroendocrine tumours occasionally may appear to have nucleoli - one should see good nucleoli in 3-4 cells in one field.
- Abundant cytoplasm - virtually excludes small cell carcinoma.
- Vacuoles with mucin (pink discolouration) - virtually diagnostic, though only seen occasionally.
- Eccentric nucleus.
- Negatives: NO moulding.
- Important if no nucleolus obvious.
Liver FNA. Elevated AFP. Diagnosis?
Hepatocellular Carcinoma
- Architecture - single cells and large clusters:
- Cohesive clusters of cells (hepatocytes) surrounded by endothelial cells - diagnostic.
- Capillaries traversing the fragments.
- Cells:
- Central nucleus +/-prominent nucleoli, +/-nuclear inclusions.
- +/-Multinucleation.
- +/-Yellow cytoplasmic pigment (bile).
- +/-Nuclear atypia.
- +/-High NC ratio.
- Notes:
- Low grade HCC is composed of cytologically normal appearing cells; the arrangement is what is diagnostic of malignancy.
- Fibrolamellar HCC has very large cells.
FNA of sacrococcygeal mass in 50 year old male. Diagnosis?
Chordoma
- Abundant myxoid background
- Tumour cells singly or in groups or cords
- Network of myxoid material round single cells and groups
- Many tumour cells have vacuolated cytoplasm
- Physaliferous cells.
*BELOW: Chordoma w/o characteristic myxoid background, imititating clear cell carcinoma. Other diagnostic pitfalls include chondrosarcoma and mucous producing adenocarcinomas.
FNA of cystic breast lesion.
Diagnosis?
Benign Apocrine Cells
(in benign fibrocystic change)
- Proteinaceous granular debris
- Macrophages and a moderate number of benign apocrine cells
- Occasionally, the apocrine cells show degenerative changes that may be mistaken for atypia
CSF of elderly patient.
Diagnosis?
Metastatic Adenocarcinoma
- The cytological features depend on the primary site
- Carcinomas form cohesive sheets and nests of atypical cells
- Nucleolar prominence
- Necrotic background
- Adenocarcinomas may have intracytoplasmic mucin droplets and form glandular structures
- Squamous carcinomas have single cells and sheets of cells with focal keratinisation and hyperchromatic, and atypical nuclei
68 year old female with PMB. Liquid based cervical cytology specimen obtained.
Diagnosis?
Malignant Melanoma
- Pleomorphic single cells or dissociating groups
- Eccentric nuclei and prominent nucleoli
- Intranuclear cytoplasmic inclusions
- Melanin may be visible
- Tumour diathesis.
- The diagnosis of melanoma of the cervix may be suggested by exfoliative or FNA cytology
58 year old male, recently undergone chemotherapy for high grade urothelial carcinoma. Urine cytology shown.
Diagnosis?
Polyomavirus (BK virus)
- Human polyomavirus infected cells have a high nuclear to cytoplasmic ratio and the blue to green cytoplasm is often eccentrically visible along one side of the cell to give the appearance of a comet.
- The inclusions may be so degenerate that the infected cell nuclei have a cleared or empty appearance.
- The inclusions may be seen without associated cytoplasm, imitating a stripped nucleus, which is unusual for a high-grade urothelial carcinoma.
- These infected cells are always seen singly and are generally small.
- Usually hyperchromatic, engendering the name “decoy cells”.
- Immunocompromised patients are especially vulnerable to BK virus reactivation (chemo).
Thyroid FNA. Diagnosis?
Papillary Thyroid Carcinoma
- Cellular aspirate with little colloid
- Papillary fronds and sheets of cells
- Dense blue-grey cytoplasm with well-defined cell boundaries
- Intranuclear inclusions
- Nuclear grooves
- Psammoma bodies
- Multinucleate histiocytes particularly where there is cystic degeneration
- ‘Chewing-gum’ colloid.
Pleural fluid from a 28 year old male with HIV. Diagnosis?
Blastomyces infection.
- Usually Blastomyces dermatitidis - fungus.
- May be in the oral cavity.
- Features:
- Broad-based budding yeast – is Blastomyces.
- The interface between two separating fungi, i.e. fungi in the process of reproducing, is very large.
- Broad-based budding yeast – is Blastomyces.
- DDx:
- Cryptosporidiosis.
Smear (A) and CSF cytology (B). Diagnosis?
Chordoma
- Cytological findings:
- Myxoid stroma
- Polyhedral vacuolated physaliphorous cells with rounded nuclei in cords and strands.
- Diagnostic pitfalls:
- May be difficult to distinguish from chondrosarcoma intraoperatively.
What are the criteria for adequacy and quality indicators in anal pap smears?
- Not well defined, but generally accepted as:
- 2,000 - 3,000 nucleated squamous cells (for conventional smears).
- Equivalent to an average of 1 -2 NSC/HPF for ThinPrep
- Equivalent to an average of 3 -6 NSC/HPF for SurePath
- 2,000 - 3,000 nucleated squamous cells (for conventional smears).
- Quality indicator:
- Adequate sampling of anal transition zone.
- Rectal columnar cells and/or squamous metaplastic cells
- Adequate sampling of anal transition zone.
Obese male with SOB and 20lb weight loss. Thoracentesis performed.
Large B Cell Lymphoma
- More readily diagnosed by BAL or FNA than in sputum
- Large cell lymphomas easier to diagnose than small/mixed
- Loosely aggregated lymphoid cells, intact cytoplasm
- Vesicular nuclei, no moulding, nucleoli visible
- Subtyping possible in BAL and FNA material.
- Ddx:
- Carcinoma - esp. small cell carcinoma.
- Anaplastic large cell lymphoma (ALCL).
- Follicular lymphoma.
- If a nodular architecture is present it is follicular lymphoma.
- Post-transplant lymphoproliferative disorder (PTLD) - in organ transplant recipients.
- Primary effusion lymphoma - seen in HIV infections.
- Mixed cellularity Hodgkin lymphoma - esp. for T-cell/histiocyte-rich large B cell lymphoma.
- B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and classical Hodgkin lymphoma.
- Other small round cell tumours.
