ABPath Cytopathology cheat sheet

Bethesda cervical category risk of CIN3+: NILM <1%, ASC-US ~4%, LSIL ~14%, ASC-H ~26%, HSIL ~60%+; management escalates with risk.

Bethesda 2014 adequacy: minimum ~5,000 well-visualized squamous cells for conventional smears; liquid-based preparations require ~5,000 cells as well, with obscuring factors documented.

HPV cotesting: negative HPV with NILM allows 5-year screening interval in average-risk patients; HPV16/18 positive with NILM warrants immediate colposcopy regardless of cytology.

Endocervical adenocarcinoma in situ: hyperchromatic crowded groups with rosettes, feathering, and nuclear pseudostratification; distinct from HSIL by glandular architecture and apoptosis.

Endometrial cells reported in patients ≥45 years are abnormal (per Bethesda); in patients <45 they may be reported as benign if menstrual timing explains them.

Anal cytology uses Bethesda-like terminology; HSIL in HIV-positive MSM warrants high-resolution anoscopy, since sensitivity of anal cytology is limited.

Koilocytes define LSIL: enlarged nuclei with raisin-like chromatin and perinuclear halo; LSIL does not require colposcopy in most algorithms (repeat in 1 year).

Glandular cell abnormalities: AGC-NOS, AGC-favor neoplastic, AIS, and adenocarcinoma; AGC carries meaningful risk and requires colposcopy with endocervical sampling and endometrial sampling if ≥35 or risk factors.

Thyroid Bethesda categories and malignancy risk: I nondiagnostic, II benign ~<3%, III AUS/FLUS ~10-30%, IV follicular neoplasm ~25-40%, V suspicious ~50-75%, VI malignant ~97-99%.

Papillary thyroid carcinoma FNA: papillary clusters, nuclear grooves, intranuclear pseudoinclusions, and powdery chromatin; psammoma bodies may be seen.

Salivary gland Milan System: categories I-VI with risk stratification; pleomorphic adenoma shows fibrillary chondromyxoid stroma with plasmacytoid/myoepithelial cells.

Lung FNA/EBUS: adenocarcinoma vs squamous cell carcinoma differentiation may require immunostains (TTF-1/Napsin A vs p40/p63); small cell carcinoma shows molding, salt-and-pepper chromatin, scant cytoplasm.

Pancreaticobiliary FNA: Papanicolaou Society categories; adenocarcinoma shows crowded overlapping clusters with nuclear contour irregularity and necrosis.

Cerebrospinal fluid: normal adult CSF has 0-5 mononuclear cells/µL; malignant cells in CSF often show high N:C ratio, prominent nucleoli, and clustering.

Pleural fluid: malignant mesothelioma vs adenocarcinoma requires immunostains (calretinin, WT1, CK5/6 vs MOC-31, Ber-EP4, CEA, TTF-1).

Rapid on-site evaluation (ROSE) improves adequacy rates and triage for ancillary testing (flow cytometry, cell block, molecular).

Fine needle aspiration of lymph node: metastatic squamous cell carcinoma vs reactive hyperplasia distinguished by keratinization and atypia; flow cytometry aids lymphoma diagnosis.

CLIA '88 cytology workload limit: no cytotechnologist may examine more than 100 slides in 24 hours; screening limited to 7.5 hours per day.

Cytology laboratory must enroll in a proficiency testing program and undergo biennial inspection; cytotechnologists evaluated with 10-slide/10-minute locator and 20-slide proficiency tests.

CLIA requires 5-year retention of cytology slides (negative) and 5 years for records; 10% rescreen of negative Pap tests is mandated for laboratories (random and high-risk).

CAP accreditation and Joint Commission standards apply; quality metrics include ASC-US/LSIL ratio (target ~2:1 to 3:1) and HSIL+ correlation with histology.

Levey-Jennings charts monitor quality control with ±2SD warning and ±3SD rejection rules; Westgard rules flag systematic and random error.

Budget variance analysis: variance = actual − budgeted; favorable variance for expenses means actual < budgeted.

FTE calculation: total paid hours ÷ 2,080 (annual hours per FTE); productivity measured as slides or tests per FTE per year.

Risk management: incident reports are non-punitive; root cause analysis (RCA) identifies system failures, and failure mode effects analysis (FMEA) is proactive.

Turnaround time (TAT) monitoring: track from specimen receipt to report; CAP requires documented TAT benchmarks for critical results.