Atypical fibroxanthoma with perineural or intraneural invasion: report of two cases

Abstract

We report two cases of atypical fibroxanthoma (AFX) that both had the previously unreported feature of neural invasion (one perineural and the other intraneural). AFXs recur in approximately 10% of cases but only rarely metastasize. Features associated with recurrence are inadequate excision and invasion into fat. Features associated with metastasis include recurrence, vascular invasion, deep tissue invasion, and tumor necrosis. Both of these tumors invaded deeply into subcutaneous fat and reached the deep fascia. Some authors would regard such cases as malignant fibrous histiocytoma (MFH) because of such deep extension; however, the concept of AFX as a superficial variant of MFH is outmoded--AFX is a distinct clinicopathologic entity with established clinical, histological, and immunohistochemical features.

Malignant fibrous histiocytoma: Changing perceptions and management challenges

“…Even contemporary dermatologic literature often regards these tumors as simply representing a deeper, more aggressive variant of atypical fibroxanthoma (AFX) as these tumors may share a nonspecific clinical appearance and exhibit a similar pleomorphic spindle cell morphology on light microscopy. [1][2][3][4][5] Several recent studies, however, have described unique molecular and morphologic features, alongside behavioral features, of MFH that are not found in AFX or other tumor types. [6][7][8][9] The goal of this review is to analyze the current medical and scientific literature regarding MFH from the perspective of the practicing clinician in order to provide practical guidance regarding diagnosis and management of these tumors.…”

Procollagen 1 and Melan-A Expression in Desmoplastic Melanomas

“…Furthermore, AFX and DM share some microscopic similarities including a predominantly spindle cell tumor in actinically damaged dermis with nuclear atypia, mitotic figures, and close proximity to the epidermis. [6][7][8][9] Histopathologically, the most reliable clue to differentiate DM from AFX is the presence of an overlying melanoma in situ component. Nevertheless, if lesions do not display epidermal involvement or ulceration does not allow an accurate judgment, the histologic differentiation remains uncertain.…”

CD117 Immunoreactivity in Atypical Fibroxanthoma

“…These bizarre, atypical cells have varying amounts of eosinophilic and occasionally lipid-containing cytoplasm with numerous mitotic figures. 1,10,11 The variants of AFX reported in the literature include spindle cell, granular, pigmented, chondroid, osteoid, osteoclastic, and clear cell types. 9,11 Though described as an indolent lesion, local recurrence and rare metastasis to the lung have been reported in the literature.…”

“…16 Local recurrence, vascular invasion, deep-tissue invasion, tumor necrosis, and perineural invasion of AFX are all features that are seen more frequently than metastatic AFX itself. 11,13 Historically c-kit has been an important diagnostic adjunct for gastrointestinal stromal tumors and hematopoietic malignancies. Gastrointestinal stromal tumors are known to be vimentin positive and selectively positive for desmin, muscle actins, and S100.…”