Cytopathology: Gynecologic and Non-Gynecologic
Cytopathology tests adequacy, sampling, morphologic criteria and reporting categories in cervical and non-gynecologic specimens. The exam expects Bethesda terminology for cervical/vaginal samples and Milan-style risk stratification for thyroid fine-needle aspiration.
Core rules
- Adequacy depends on specimen type, cellularity and preservation; unsatisfactory samples cannot exclude disease.
- Cervical cytology uses squamous and glandular criteria. LSIL shows koilocytosis and low-grade nuclear enlargement; HSIL shows high nuclear-to-cytoplasmic ratio, hyperchromasia, irregular membranes and loss of polarity.
- ASC-US is a squamous abnormality indefinite for dysplasia; ASC-H is suspicious for HSIL and needs colposcopy.
- Glandular lesions require attention to nuclear crowding, rosettes and background; AGC is not a diagnosis of malignancy.
- Non-gynecologic fluids are assessed for cellularity, background and cell clusters; thyroid FNA uses Bethesda categories I to VI.
Worked example
A 35-year-old woman has a Pap test showing crowded sheets of small cells with high nuclear-to-cytoplasmic ratio, hyperchromatic nuclei and loss of polarity. No invasion or tumor diathesis is seen. The Bethesda category is HSIL. Reasoning: the features are high-grade squamous, not reactive atrophy, and HSIL warrants colposcopy with biopsy. Invasion cannot be diagnosed on cytology alone.
Traps
Do not call koilocytosis HSIL. Atrophy can mimic HSIL; look for smooth nuclear contours and lack of high-grade atypia. Air-drying causes nuclear enlargement and pale chromatin. Obscuring blood or inflammation may require repeat sampling. A negative cytology does not exclude cancer.