Atypical fibrous histiocytoma, pseudosarcomatous fibrous histiocytoma, dermatofibroma with monster cells

Clinical features

This is a relatively uncommon lesion. It is seen most frequently on the lower extremities of young to middle-aged adults.

Histopathology

The lesion is mainly epidermal, but may show extension into the superficial subcutis(19/591). Pleomorphic cells are set in a background of classical fibrous histiocytoma. There is a spectrum from lesions showing only focal mild pleomorphism to those exhibiting marked pleomorphism.

Immunohistochemistry

SMA	10/42, focal
CD34	2/42, focal
CD68	0/42
desmin	0/42
Cam5.2	0/42
MNF-116	0/42
factor XIIIa	0/42
NKI-C3	2/2, focal
NSE	2/2, focal
S-100	0/42

Differential diagnosis

DFSP; usually lacks marked pleomorphism, lacks epidermal hyperplasia, CD34 strongly positive
atypical fibroxanthoma; usually presents on the head or neck of elderly patients, associated with actinic elastosis, lacks a grenz zone, lacks epidermal hyperplasia, lacks entrapped hyalinised collagen bundles, does not extend into subcutis. Pleomorphism is more diffuse.
(angiomatoid) MFH; predominantly subcutaneous, thick fibrous pseudocapsule, lymphoplasmacytic infiltrate and haemorrhage, desmin and EMA may be positive
pleomorphic fibroma of skin; cellularity is sparse, lacks epidermal hyperplasia and classical features of fibrous histiocytoma
leiomyosarcoma; intersecting bundles of eosinophilic spindle cells, cigar-shaped nuclei, usually lacks marked pleomorphism, desmin positive.
malignant melanoma; S-100 positive
spindle cell squamous cell carcinoma; cytokeratin positive
pseudosarcomatous fibroepithelial stromal polyp; usually vulval, polypoidal, lacks epidermal hyperplasia, lacks a grenz zone,
cutaneous angiosarcoma; spindle cells positive for both CD31 and CD34.

Management

Complete excision with clear margins

Prognosis

Atypical fibrous histiocytoma may recur, particularly in inadequately excised. Rarely, it may metastasis (2/591)and may prove fatal (1/591).

References

1Kaddu, S., M. E. McMenamin, et al. (2002). "Atypical fibrous histiocytoma of the skin: clinicopathologic analysis of 59 cases with evidence of infrequent metastasis." Am J Surg Pathol 26(1): 35-46.

This page last revised 7.5.2002.