Accuracy of Intraoperative Frozen Section Analysis of Sentinel Node Biopsies in Penile Cancer

In penile squamous cell carcinoma (PSCC), surgical nodal staging can be performed using the dynamic sentinel node biopsy (DSNB) procedure. This study aimed to evaluate the diagnostic accuracy of intraoperative frozen section analysis of sentinel nodes (SNs) for the detection of inguinal metastases.

Between 2011 and 2025, 89 patients underwent unilateral (n = 18) or bilateral (n = 71) DSNB with intraoperative frozen section analysis during PSCC surgery. Clinicopathological variables and disease course were registered. Diagnostic accuracy of frozen section analysis compared with final histopathology was assessed across 160 groin examinations.

No false-positive frozen section results were observed. There were 19 true-positive, 139 true-negative, and 2 false-negative cases. Both false-negative examinations contained micrometastatic deposits measuring 0.4 mm and 1.2 mm located outside the plane of the frozen sections. Sensitivity and specificity were 0.90 (95% confidence intervals [CI]: 0.70-0.99) and 1.00 (95% CI: 0.97-1.00), respectively. Inguinal metastases were identified on frozen sections in 16 of 89 patients (18%), including 13 unilateral and 3 bilateral cases. Metastatic deposits ranged in size from 1.1 mm to 31.5 mm. During a median follow-up of 27 months, only one groin recurrence occurred among the 160 investigated groins.

Intraoperative frozen section analysis of sentinel lymph nodes appears to be a safe, reproducible, and accurate method for detecting inguinal lymph node metastases. The findings led to intraoperative changes in management in approximately one in 5 patients, underscoring its potential clinical impact. However, micrometastatic disease may still be missed, and in cases with negative frozen section findings, definitive treatment decisions should await final histopathological assessment.