P194 A 75-patient single-centre evaluation of excision margins and recurrence for atypical fibroxanthoma and pleomorphic dermal sarcoma: real-world UK outcomes suggesting low recurrence with margins < 9 mm (2014–2020)

Abstract

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) exist on a clinicopathological spectrum but currently require different management due to reported higher metastatic risk associated with PDS. European guidelines (published 31 January 2022) recommend 20-mm safety margins with micrographically controlled excision for PDS. In the UK, Mohs surgery is not always available, and wide margins may be impractical. We evaluated excision margins and recurrence for AFX and PDS managed with pragmatic excision margins in a UK single-centre setting. A retrospective review was conducted of 75 consecutive patients treated for AFX or PDS between 2014 and 2020 at a hospital trust in South East England. Data collected included demographics, tumour size, histological diagnosis, excision margin and recurrence. In total, 87% of patients were male, and the average age was 80 years (range 49–97). Tumour size ranged from 5 to 60 mm. Histology identified PDS in 28% of cases (n = 21), AFX in 31% (n = 23) and mixed AFX/PDS diagnoses in 41% (n = 31). The mean clinical excision margins were 8.5 mm for PDS, 5 mm for AFX and 6 mm for AFX/PDS. Mohs surgery was not used in any cases. Clear histological margins were achieved in 95% (n = 71). Four local recurrences occurred: three with AFX and one with AFX/PDS; notably there were none for PDS. There were no regional metastases, and one distal metastasis to lung occurred in an immunosuppressed transplant patient with AFX. No routine imaging surveillance was undertaken. Pragmatic excision margins, substantially smaller than current European recommendations, achieved high clearance rates and low recurrence, notably for PDS. These findings suggest that routine use of Mohs surgery and 20-mm margins, and routine imaging, may not be necessary in all cases in the UK. Larger, multicentre UK studies, ideally prospective, would be desirable to inform UK-specific guidelines to optimize management for AFX and PDS.