Role of Multiple Scouting Biopsies before Mohs Micrographic Surgery for Extramammary Paget's Disease

Background. Extramammary Paget's disease (EMPD) frequently extends subclinically, resulting in high recurrence rates after surgical excision. Mohs micrographic surgery (MMS) improves cure rates but may require time-consuming reexcision of subclinical extension. A mechanism to estimate the location and extent of subclinical extension would be helpful.
Objective. To describe and evaluate a technique for multiple scouting biopsies before MMS for EMPD.
Method. A retrospective review of patients at Mayo Clinic who had multiple scouting biopsies before MMS for EMPD without dermal invasion.
Technique. The clinical extent of EMPD is identified. The scouting biopsy sites are determined and documented with photographs. The scouting biopsy specimens are sent for permanent sections. The results of the scouting biopsies help guide the extent of the initial Mohs layer. The tumor is cleared with MMS. An additional 1 mm peripheral margin of tissue is usually submitted for permanent sections.
Results. Multiple scouting biopsies were done in five patients. Four of the five patients had at least one true-positive result. At least one true-negative result was obtained in all five patients. Two patients had at least one false-negative result.
Conclusion. Multiple scouting biopsies before MMS for EMPD without dermal invasion can be a beneficial adjuvant technique.
DAVID L. APPERT, MD, CLARK C. OTLEY, MD, P. KIM PHILLIPS, MD, AND RANDALL K. ROENIGK, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS.