ABPath Cytopathology 3 — Questions and Answers
Question 1: In a pancreatic FNA obtained by endoscopic ultrasound, elevated cyst fluid CEA most strongly suggests which lesion?
- Mucinous cystic neoplasm (Correct answer)
- Serous cystadenoma
- Pseudocyst
- Solid pseudopapillary neoplasm
Correct answer: Mucinous cystic neoplasm
High cyst fluid CEA indicates a mucinous (potentially premalignant) cystic neoplasm.
Question 2: A salivary gland FNA shows a biphasic pattern of epithelial cells and metachromatic fibrillary stroma on Diff-Quik. Which diagnosis is favored?
- Pleomorphic adenoma (Correct answer)
- Warthin tumor
- Mucoepidermoid carcinoma
- Acinic cell carcinoma
Correct answer: Pleomorphic adenoma
The magenta fibrillary myxochondroid stroma with epithelial cells is classic for pleomorphic adenoma.
Question 3: Which lung cytology feature is most characteristic of small cell carcinoma?
- Nuclear molding with salt-and-pepper chromatin and scant cytoplasm (Correct answer)
- Abundant keratinized orangeophilic cytoplasm
- Large cells with prominent macronucleoli and vacuoles
- Cells forming acinar structures with mucin
Correct answer: Nuclear molding with salt-and-pepper chromatin and scant cytoplasm
Nuclear molding, fine granular chromatin, scant cytoplasm, and apoptosis characterize small cell carcinoma.
Question 4: On CSF cytology, which finding is most concerning for leptomeningeal carcinomatosis?
- Clusters of atypical epithelial cells with high N/C ratio (Correct answer)
- Predominance of small mature lymphocytes
- Numerous neutrophils and bacteria
- Occasional reactive monocytes
Correct answer: Clusters of atypical epithelial cells with high N/C ratio
Malignant epithelial cell clusters in CSF indicate metastatic (leptomeningeal) spread.
Question 5: Which immunostain panel best distinguishes lung adenocarcinoma from mesothelioma in an effusion?
- TTF-1 and MOC-31 positive, calretinin negative (Correct answer)
- Calretinin and WT-1 positive, BerEP4 negative
- CK20 and CDX2 positive
- p40 and CK5/6 positive only
Correct answer: TTF-1 and MOC-31 positive, calretinin negative
TTF-1 and MOC-31 positivity with calretinin negativity supports pulmonary adenocarcinoma over mesothelioma.
Question 6: A liver FNA shows enlarged hepatocyte-like cells with increased N/C ratio and thickened trabeculae wrapped by endothelium. Which lesion is most likely?
- Hepatocellular carcinoma (Correct answer)
- Focal nodular hyperplasia
- Hepatic adenoma
- Regenerative nodule
Correct answer: Hepatocellular carcinoma
Thickened trabeculae with endothelial wrapping and increased N/C ratio favor hepatocellular carcinoma.
Question 7: Which stain is used to identify Pneumocystis jirovecii cysts in bronchoalveolar lavage specimens?
- Gomori methenamine silver (GMS) (Correct answer)
- Congo red
- Prussian blue
- Mucicarmine
Correct answer: Gomori methenamine silver (GMS)
GMS stains the cyst walls of Pneumocystis jirovecii black.
ABPath Cytopathology 3
In a pancreatic FNA obtained by endoscopic ultrasound, elevated cyst fluid CEA most strongly suggests which lesion?