Achieving Adherence With NCCN Guidelines for Nonmelanoma Skin Cancer Regarding Peripheral and Deep En Face Margin Assessment (PDEMA)

Peripheral and deep en face margin assessment (PDEMA), formerly termed by NCCN as complete circumferential peripheral and deep margin assessment (CCPDMA), has the advantages of histologic visualization of the entire marginal surface, highly accurate resection of involved tissue, and sparing of uninvolved tissue. Owing to its highest reported cure rates, PDEMA is the NCCN-preferred treatment for dermatofibrosarcoma protuberans, high-risk basal cell carcinoma, and very-high-risk cutaneous squamous cell carcinoma. In the United States, Mohs micrographic surgery (Mohs) is the most common method of PDEMA. In Germany and some other countries, non-Mohs methods of PDEMA referred to as the Tubingen torte and muffin techniques are more widely used. The Tubingen methods of PDEMA require close communication between surgeon and pathologist. This article describes the background of both Mohs and Tubingen PDEMA, reviews what constitutes PDEMA, and provides a protocol for Tubingen PDEMA detailing critical components in a stepwise fashion using illustrative photos and diagrams. We hope to broaden understanding of the NCCN Guidelines and their rationale, align practice, and optimize patient outcomes.