Superficial malignant fibrous histiocytoma presenting as recurrent atypical fibroxanthoma

Abstract

Atypical fibroxanthoma (AFX) and malignant fibrous histiocytoma (MFH) are neoplasms of probable fibrohistiocytic lineage. The precise relationship between AFX and MFH remains controversial. We present two cases in which a lesion was excised from the face of an elderly person and reported as AFX. Both cases recurred within 12 months and were reclassified as MFH. They were excised with slow Mohs' micrographic surgery, with adjuvant radiotherapy in one case. In the other, a further recurrence was treated with orbital exenteration and radiotherapy. We review the difficulties in differentiating between AFX and MFH and the implications for treatment.

Case of atypical fibroxanthoma in the palpebral conjunctiva

“…A differential expression of CD74 by atypical fi broxanthoma and malignant fi brous histiocytoma was reported to distinguish these two lesions, and a weak positivity for CD74 was reported in atypical fi broxanthomas in earlier publications. 1,2,6 It has been reported that atypical fi broxanthoma demonstrates moderate to strong diffuse staining with CD99, in contrast to malignant fi brous histiocytoma, which shows weak and focal immunoreactivity. 7 Our case showed a weak immunoreactivity for CD74 and CD99, and MIB-1 index was about 10%.…”

“…1,2 Most patients have a long history of sun exposure, and an antecedent trauma is also one of the risk factors. The size of most atypical fi broxanthomas is 1-2 cm.…”

“…5 Because an atypical fi broxanthoma is histologically similar to malignant fi brous histiocytoma, discrimination between a malignant fi brous histiocytoma and an atypical fi broxanthoma is diffi cult. 1,2,4 Occupational and therapeutic radiation is a possible predisposing factor for malignant fi brous histiocytoma of the head and neck. 2 Our patient had no history of irradiation.…”

“…1,2 Several spindle cell tumors can be differentiated using immunohistochemical staining. 1,2,4 Negative immunostaining for desmin, α-SMA, S-100, and GFAP were used to rule out leiomyosarcoma and malignant schwannoma. The histiocytic marker CD68 was positive in our case.…”

Atypical fibroxanthoma

“…AFX and MFH may have been differentiated based upon positivity for CD74, in which reduced immunoexpression for CD74 in AFX is characterized compared to that in MFH (Lazova R et al 1997). Further examination will be necessary in order to confi rm the reliability of CD74 as a marker with which to differentiate between AFX and MFH (Ly H et al 2004).…”