Conception and Management of a Poorly Understood Spectrum of Dermatologic Neoplasms: Atypical Fibroxanthoma, Pleomorphic Dermal Sarcoma, and Undifferentiated Pleomorphic Sarcoma.

Opinion Statement: Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) tumors share many clinical, etiologic, and histologic features and likely represent components of a tumor spectrum. In dermatologic oncology, differentiating between AFX and PDS is pivotal as tumors with histological features consistent with PDS are more likely to behave in a clinically aggressive manner. Importantly, the term "pleomorphic dermal sarcoma" (PDS) is a more appropriate designation than "undifferentiated pleomorphic sarcoma" (UPS) for describing deeper, more aggressive, histologically high-grade cutaneous tumors that otherwise resemble AFX. Surgery remains the gold standard for treatment. In the setting of AFX, excision with the Mohs micrographic technique appears to offer superior tumor control rates while maintaining greater tissue preservation over wide local excision and should be considered first line. In the setting of PDS, optimal management is less clear given the paucity of available data. However, due to its greater propensity to recur and metastasize, extirpation with complete tumor margin control appears paramount. The roles of imaging and SLNB in management and clinical outcomes of AFX and PDS are unclear given the lack of available data. In reality, these tools are unlikely to be helpful in most cases of AFX. However, in the setting of PDS, emerging literature indicates that these tumors are inherently higher risk, and thus, imaging and SLNB may be helpful in select cases. Additionally, radiation therapy may be of adjuvant benefit for these tumors when clear surgical margins cannot be obtained. While traditional chemotherapy has been largely ineffectual, the recent discovery of key oncogenetic mutations has allowed for the identification of several potential molecular drug targets that may have a therapeutic role with future study. In the unfortunate setting of metastatic disease, a multidisciplinary approach is optimal. Further studies are needed to establish definitive conclusions regarding risk stratification and best management practices.