Dermatofibrosarcoma Protuberans in South Africa: Outcomes of Staged Excision and Peripheral and Deep En Face Margin Assessment (PDEMA) and Recommendations for Wide Local Excision Margins

Background: Dermatofibrosarcoma protuberans (DFSP) is a rare, locally aggressive tumour with recurrence rates of 10-60% after wide local excision (WLE).Surgical excision with peripheral and deep en face margin assessment (PDEMA) offers superior cure rates (1.11%).Objective: To report the outcomes of staged excision (SE) with PDEMA for DFSP in South Africa and to propose a pragmatic approach to selecting WLE margins when PDEMA is unavailable.Methods: Nineteen DFSP patients underwent staged excision (SE) with PDEMA.Data collected included tumour and defect size, margin required for clearance, complications, recurrence, and tissue sparing.Using our margin-clearance data, we projected the defect sizes required for complete clearance with WLE and compared these with the actual defect sizes from our cases.Tissue preservation was calculated and analysed for statistical significance using non-parametric tests.Results: Complete margin clearance was achieved in all cases, with no complications or recurrences at a median 35-month follow-up.DFSPs were stratified into three groups: a) small primary DFSP (<1cm diameter); b) large primary DFSP (>1cm diameter) and c) recurrent DFSP.Peripheral margins needed to clear all tumours: a) 2cm, b) 4cm, c) 5cm.Tumour extension beyond the deep fascia was observed in all groups, suggesting that WLE depth should extend below the deep fascia if PDEMA is not utilised.SE with PDEMA achieved significant tissue preservation. Limitations:The small sample size limits generalisability.