Atypical fibroxanthoma and pleomorphic dermal sarcoma: Is superficial infiltration in subcutaneous tissue acceptable in AFX?

• Published in: Annals of diagnostic pathology Vol. 58; p. 151915
• Main Authors: van Midden, Dominique, Flucke, Uta E., Amir, Avital L., Bonenkamp, Johannes J., Lubeek, Satish F.K., Blokx, Willeke A.M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.06.2022
• Subjects: Atypical fibroxanthoma; Pleomorphic dermal sarcoma; Prognosis; Recurrence; Pleomorphic dermal sarcoma; Recurrence; Prognosis; Atypical fibroxanthoma
• ISSN: 1092-9134; 1532-8198
• DOI: 10.1016/j.anndiagpath.2022.151915

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are rare cutaneous neoplasms forming a spectrum. Case reports with recurrences and metastasis have been published despite the current view that AFX is benign. The aim of this study was to identify clinical and histopathological features that predict tumor recurrence. A retrospective review of AFX and PDS cases was performed. Clinical characteristics were obtained from patient records. A total of 29 AFX and 23 PDS cases were identified. Review led to re-classification of 12 cases (18%). In 14/50 (26.9%) cases a recurrence occurred. Recurrences were significantly more likely to occur when the tumor showed any infiltration in the subcutaneous fat (100% vs 43.2%, p = 0.000) or when the tumor diameter exceeded 2 cm (46.2% vs 16.2%, p = 0.030). This study shows that histopathological distinction between AFX and PDS remains difficult with reclassification in 12 out of 52 (18%) cases upon review. All AFX cases solely confined to the dermis behaved benign. We therefore advocate to classify all cases with any form of subcutaneous extension as PDS, and only lesions without as AFX. This contrasts with the current general opinion in which superficial subcutaneous invasion is still accepted in AFX. •AFX lesions are strictly confined to the dermis and behave benign without recurrences.•Differentiation between AFX and PDS is essential to predict patient outcome and guide treatment decisions.•Approximately one third of PDS cases is underdiagnosed as AFX.