DS05 The UK’s first outcome analysis of atypical fibroxanthoma and pleomorphic dermal sarcoma from a major tertiary centre

Abstract Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are rare cutaneous malignancies that predominantly affect older individuals, often arising in sun-exposed areas. This study represents the first UK-based outcome analysis of AFX and PDS from a major tertiary hospital, reviewing all cases diagnosed between January 2014 and 20 August 2019. A retrospective cohort study identified 94 patients initially diagnosed with AFX. Of these, 15 cases were reclassified as PDS, leaving 79 confirmed AFX cases. Separately, 42 patients were identified with PDS. Patient demographics, lesion characteristics, histopathological features, treatment modalities and follow-up outcomes were analysed. AFX predominantly affected men (n = 74, 94%), and the patients had a median age of 79 years. Six patients were immunosuppressed. Most lesions (n = 76, 96%) were on the head and neck. Histopathological findings showed dermal involvement in 53 cases, subcutaneous extension in 13, and fascia involvement in one. Mitosis was present in 38 cases, necrosis in two, and perineural invasion (PNI) in one. Lymphovascular invasion was identified in three cases. Excision was incomplete in three cases, and five had narrow margins. PDS was more frequent in men (n = 36, 86%) and the median age was 81 years. Eight patients were immunosuppressed or had related conditions. Most lesions (n = 40, 95%) were on the head and neck. Tumours extended into the subcutis in 26 cases, fascia in 10, and bone in four. Mitosis was present in 36 cases, necrosis in six, PNI in nine (one suspected) and lymphovascular invasion in one. Excision was incomplete in three cases, and 15 had narrow margins. In AFX, no deaths, recurrences or metastases were observed. Follow-up varied: 35 patients were monitored for 1–2 years, 17 for > 2 years, and nine for < one year. Five patients had no follow-up (1 due to death). In PDS, five deaths were attributed to the condition, with one contributory case. Imaging at diagnosis was performed in 27 patients. Local recurrence occurred in nine cases, distant recurrence in seven (one likely but unproven) and lymph node metastasis in three. Some patients were followed for up to 10 years, while others had follow-up cut short due to death or ill health. In conclusion, AFX and PDS primarily affect older men, with lesions commonly occurring on the head and neck. AFX exhibited a favourable prognosis, with no recurrences or disease-related mortality, whereas PDS demonstrated a more aggressive clinical course, with a higher recurrence rate, more distant metastases and greater disease-related mortality. This study is the first UK-based outcome analysis of AFX and PDS from a large tertiary hospital.