Positive KI67 and periodic acid-schiff mandates wider range of excision in scrotal extramammary Paget's disease.

Background: Extramammary Paget's disease (EMPD) of the scrotum is a rare disease that requires surgical excision. A positive margin is related to recurrence and poorer prognosis. We aimed to investigate the expression of Ki67 and periodic acid-Schiff (PAS) in a biopsy sample and to evaluate their predictive value in true margin status.

Methods: Sixty-four patients with noninvasive scrotal EMPD were included. Immunohistochemical staining of Ki67 and PAS was reviewed and compared statistically with the margin status of intraoperative frozen section examination (FSE).

Results: Seventeen of 64 patients had a positive margin discovered at the first FSE. Expression of Ki67 was not significantly different between positive and negative margin status (p = .16). Expression of PAS was higher in samples with positive margins (p = .05). The incidence of positive margins was significantly higher in the double-positive group than in the double-negative group (p = .03).

Conclusion: Positive expression of both factors in a biopsy sample requires wider excision to ensure negative margins.