PR12 ATYPICAL FIBROXANTHOMA AND MALIGNANT FIBROHISTIOCYTOMA – A TEN‐YEAR REVIEW

Abstract

Purpose: To review the clinical and histological differences between atypical fibroxanthoma (AFX) and malignant fibrohistiocytoma (MFH).Methodology: Cases of MFH and AFX were identified and histologically reviewed from our non‐melanoma skin cancer (NMSC) database 1996–2007 for the Central Region of New Zealand. Medline search and recent pathology textbooks were reviewed to determine current opinion and evidence for the diagnostic differentiation between AFX and MFH.Results: Of the 54,002 cases of NMSC, 103(0.2%) were histologically reported as AFX and 14(0.03%) MFH, with a mean age of 77 (range 51–93) and 74 (28–88) years respectively. The mean size of AFX was 16.3 (5–70) mm occurring on the head & neck (n = 97), limb (n = 3), trunk (n = 2). 15 (14.7%) lesions were incomplete excised. 12 (11.7%) cases developed local recurrence and 1 metastasis. The mean size of MFH was 20.9 (range 7–50) mm occurring on the head & neck (n = 10), trunk (n = 2), groin (n = 1) and limb (n = 1). 3 (21.4%) lesions were incompletely excised. 2(14.3%) patients developed local recurrence and 2 metastases. Local recurrence occurred in 12 (11.7%) cases of AFX and 2 (14.3%) cases of MFH. The literature states clinical and histological differences between AFX and MFH, but no immunohistochemical (IHC) stain reliably differentiates between them.Conclusion: Differentiating AFX from MFH based on histology and IHC is difficult and our cases did not conform to the typical presentation indicated in the literature. AFX and MFH are likely to belong to a spectrum of soft tissue sarcomas with variable aggressiveness.