Atypical fibroxanthoma: new insights

Abstract

Atypical fibroxanthoma (AFX) is an ultraviolet radiation-associated dermal neoplasm. To address the clinicopathologic and molecular features of this particular neoplasm. The author conducted a literature review using PubMed searching for articles relating to AFX. AFX usually appears as a rapidly growing nodular or nodulo-ulcerative lesion. It occurs on sun-exposed skin of elderly peoples. AFX may be composed predominantly of pleomorphic, spindle, epithelioid cells, or admixture of these cells. The differential diagnosis of AFX includes pleomorphic dermal sarcoma, squamous cell carcinoma, malignant melanoma and leiomyosarcoma. Several observations favor a mesenchymal origin for AFX. These reviews address the clinicopathologic features, molecular pathology, prognosis and treatment of this neoplasm.

Keywords::

• atypical fibroxanthoma
• clinicopathologic
• dermal sarcoma
• pathogenesis
• ultraviolet light

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Clinically, atypical fibroxanthoma (AFX) appears as a rapidly growing light-brown, red or pink papule, nodule or nodulo-ulcerative lesion, which is usually <2 cm in diameter.

• Risk factors of AFX include exposure to ultraviolet and ionizing -radiations and immunosuppression.

• Some authorities (a correspondence between McCalmont and Fletcher) consider that AFX should be applied to tumors confined to the dermis, which lack adverse features such as deep invasion, tumor necrosis, perineural or lymphovascular invasion. AFX diagnosed using these strict criteria have essentially benign behavior. Also, many others have also expressed this view.

• Reports of metastatic AFX antedate recent immunohistochemical markers or are based on application of flawed diagnostic criteria.

• Any cytokeratin positivity in AFX is considered an extraordinary occurrence, and for practical purposes, expression of cytokeratin should rule out a diagnosis of AFX.

• Most experts now believe that the subset of AFX cases occurring on the extremities of young patients are not AFX, but rather either atypical fibrous histiocytomas or pleomorphic dermal sarcomas.

• The differential diagnosis of AFX includes: atypical fibrous histiocytoma, undifferentiated pleomorphic sarcoma, dermatofibrosarcoma protuberans, squamous cell carcinoma (sarcomatoid, spindle cell types or lesions with osteoclast-like giant cells), malignant melanoma, leiomyosarcoma, pleomorphic angiosarcoma and myofibrosarcoma. Immunohistochemistry is of great value in excluding other entities, which form the differential diagnosis.

• In the author’s opinion, AFX may develop by epithelial-mesenchymal transition of squamous cell carcinoma (epithelial origin) into a mesenchymal cancer phenotype.

Notes