Brewer, Jerry D.

BACKGROUND The use of Mohs micrographic surgery as a treatment for melanoma is rising, but the reliability of Mohs surgeons in assessing MART-1 melanoma en-face margins has not been evaluated. OBJECTIVE To evaluate interrater and intrarater reliability of Mohs surgeons in interpreting margins of early-stage melanoma. METHODS Twenty Mohs surgeons were asked to independently review images of frozen section MART-1 en-face peripheral margins of in situ or early-stage melanoma. Surgeons determined margins as positive or negative at initial evaluation and 6 weeks later. Primary outcomes were interrater and intrarater reliability. RESULTS Interrater agreement was 84.1% (95% confidence interval [CI]: 75.5%–92.8%) for assessment 1 and 87.5% (95% CI: 78.4%–96.4%) for assessment 2, with kappa values 0.68 (95% CI: 0.50–0.82) and 0.75 (95% CI: 0.57–0.88). Average intrarater percent agreement was 95.0% (95% CI: 70.6%–100.0%) with average kappa 0.90 (95% CI: 0.50–1.00). CONCLUSION Substantial interrater and nearly perfect intrarater agreement was identified among surgeons assessing melanoma margins utilizing MART-1 immunostaining, demonstrating consistent and reproducible assessment of melanoma margins during Mohs cases.

The locally aggressive nature and high recurrence rate of dermatofibrosarcoma protuberans (DFSP) make it challenging to manage, especially when present on the scalp, owing to its ability to invade the underlying periosteum, bone, dura, or brain. Preoperative imaging is used to plan resection, but the true correlation between periosteal or osseous changes on imaging and the presence of tumor within the periosteum is unclear. We present our institutional experience of managing DFSP of the scalp with emphasis on the imaging used. A retrospective review of 33 patients with DFSP of the scalp treated at a tertiary center was conducted. Data on demographics, tumor characteristics, preoperative imaging (magnetic resonance imaging or computed tomography), and surgical outcomes were analyzed. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each imaging modality were calculated. Patients underwent surgical resection at a mean age of 37.11 years and had a median follow-up of 28.34 months. Preoperative imaging was available for 26 patients (CT only: 5, MRI only: 12, CT and MRI: 9). Calvarial abnormalities were seen in 3 patients. Treatment included Mohs surgery (66.7%) and wide local excision (33.3%). In 10 patients with positive periosteal margins, bone involvement was managed by burring (7) or craniectomy (3). The sensitivity and PPV of CT for periosteal margin positivity were 25% and 100%, and for MRI were 33% and 100%, respectively. The specificity and NPV were 100% and 50% for CT, and 100% and 66% for MRI. Preoperative CT and MRI have low sensitivity and NPV but high specificity and PPV in determining depth of involvement and are essential to guiding reconstruction in DFSP of the scalp.

Background: Mohs micrographic surgery (MMS) is a promising treatment modality for melanoma in situ (MIS). However, variations in surgical technique limit the generalizability of existing data and may impede future study of MMS in clinical trials. Methods: A modified Delphi method was selected to establish consensus on optimal MMS techniques for treating MIS in future clinical trials. The Delphi method was selected due to the limited current data, the wide range of techniques used in the field, and the intention to establish a standardized technique for future clinical trials. A literature review and interviews with experienced MMS surgeons were performed to identify dimensions of the MMS technique for MIS that (1) likely impacted costs or outcomes of the procedure, and (2) showed significant variability between surgeons. A total of 8 dimensions of technical variation were selected. The Delphi process consisted of 2 rounds of voting and commentary, during which 44 expert Mohs surgeons across the United States rated their agreement with specific recommendations using a Likert scale. Results: Five of eight recommendations achieved consensus in Round 1. All 3 of the remaining recommendations achieved consensus in Round 2. Techniques achieving consensus in Round 1 included the use of a starting peripheral margin of ≤5 mm, application of immunohistochemistry, frozen tissue processing, and resecting to the depth of subcutaneous fat. Consensus on the use of Wood’s lamp, dermatoscope, and negative tissue controls was established in Round 2. Conclusions: This study generated 8 consensus recommendations intended to offer guidance for Mohs surgeons treating MIS. The adoption of these recommendations will promote standardization to facilitate comparisons of aggregate data in multicenter clinical trials.