Summary: EMPD Treatment

•Surgical excision is the standard treatment for EMPD.

•Wide local excision results in high recurrence rates.

•Mohs surgery has become the preferred method of managing many cases of EMPD due to the ability to evaluate 100% of the margin and conserve normal tissue, but has a higher recurrence rate than is seen for other cutaneous malignancies.

•The addition of CK7 immunostaining to Mohs surgery shows promise in providing more accurate margin control and lower recurrence rates.

•Scouting biopsies may be useful for preoperative estimation of margins prior to Mohs surgery.

22.6EMPD Treatment

Surgical excision of EMPD remains the mainstay of treatment. Mohs micrographic surgery has become the preferred method of managing EMPD by many practitioners due to the ability to evaluate 100% of the margin while minimizing tissue loss and morbidity.

EMPD of the vulva has been treated surgically with methods ranging from vulvectomy (partial or total) to widelocalexcisionwithmarginsof1–3cm.Vulvectomy, the most extensive and morbid procedure, has the lowest reported recurrence rate in some series (15%), compared with 43% recurrence for wide local excision. Perianal and scrotal EMPD have an even higher rate of recurrence after wide local excision, some series reporting a rate up to 50%, though some authors have achieved a recurrence rate of 9.9% using a combination of 3-cm margins and intraoperative frozen sections [7, 14].

Some studies conclude that margin status is predictive of recurrence, with positive margins leading to higher rates of recurrence [15]. While this conclusion seems intuitive, many series document recurrence of EMPD that occurs independent of margin status, with patients who have reportedly clear margins going on to develop recurrent disease. This observation may be a testament to the importance of en face evaluation of 100% of the margins of excision of EMPD, as it is likely that many of the previously reported negative margins were falsely negative, evidenced by the recent

incorporation of CK7 into Mohs surgery and the striking margin involvement not detected with routine hematoxylin and eosin staining.

22.6.1Wide Local Excision and Recommended Margin

Wide local excision of EMPD leads to widely ranging reported recurrence rates of 9.9–60%. Given the rare occurrence of EMPD and lack of randomized trials, establishing an evidence-based margin of excision is difficult. Utilizing margin control with Mohs surgery, authors have concluded that a margin of 5 cm would successfully excise EMPD in 97% of patients [26]. In this study, margins of 2 cm would have completely excised tumor in only 59% of patients. The authors recommend 5 cm margins or Mohs surgery.

Other authors have concluded that the rate of recurrence does not differ when using margins >2 cm compared to margins <2 cm [20]. Their conclusion does not entirely contradict the findings mentioned above; however, suggesting that any margin less than 5 cm may be inadequate for the excision of many cases of EMPD. Examination of a series of patients with scrotal EMPD found that with 1–2 cm margins, 36% of the tumors were excised with a positive margin [20].

The introduction of intraoperative frozen sections has allowed better margin control and a significant reduction in recurrence rates to 9.9–25% [10, 14, 15, 20] Intraoperative frozen sections, however, do not typically allow en face evaluation of 100% of the margin, in contrast to Mohs surgery. Standard cross-sec- tional processing, utilized in most excisions including those employing intraoperative frozen sections in a non-Mohs surgery setting, allows examination of around 0.1% of the total margin, leading to the potential for a high false negative rate.

It is clear that when standard excision is used to treat EMPD, relying on visual exam to determine the extent of tumor prior to excision has proven to be inaccurate, validating the significant invisible extension present in EMPD as well as the potential value of Mohs surgery in the treatment of EMPD.

22.6.2 Time to Recurrence

In a large series of patients with scrotal EMPD, the average time from surgery to diagnosis of recurrence