Cellular benign fibrous histiocytoma. Clinicopathologic analysis of 74 cases of a distinctive variant of cutaneous fibrous histiocytoma with frequent recurrence.
We report seventy-four cases of a distinctive variant of cutaneous fibrous histiocytoma, which is often mistaken histologically for sarcoma and which carries a high local recurrence rate. These tumors appeared most commonly in young or middle-aged adults, with a predominance in men (male/female ratio 1.9:1). Anatomic distribution was wide, with cases occurring mainly in the upper limb/limb girdle (34%), lower limb/limb girdle (27%), and head and neck region (20%). Most lesions had been present for only a few months, and their sizes ranged from 0.5 cm to 2.5 cm in maximum diameter. Twelve (26%) of 46 cases with follow-up (mean duration 3 years) recurred locally, in one case twice. Distinctive histologic features were a commonly fascicular growth pattern, predominance of eosinophilic spindle cells with tapering nuclei, a moderate mitotic rate (mean three per 10 high-power fields), and frequent extension into the subcutaneous fat (33% of cases). In addition, all cases showed at least focal cytologic polymorphism (inflammatory cells, foam cells, giant cells), and 58% showed associated epidermal alterations in common with usual cutaneous fibrous histiocytomas. Nine cases (12%) showed foci of central necrosis. Immunohistochemical studies (ABC method) found only vimentin and very focal smooth muscle actin positivity. Tests for CD34, desmin, S-100, keratin, and Factor XIIIa were negative in all cases. These lesions should be distinguished from dermatofibrosarcoma protuberans and leiomyosarcoma, with which many of these cases were initially confused.
Calonje
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E
Department of Histopathology, St Thomas's Hospital (U.M.D.S.), London, England.
Mentzel
T
T
Fletcher
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CD
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D018219:Histiocytoma, Benign Fibrous / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D008297:Male; D008875:Middle Aged; D008938:Mitosis; D009364:Neoplasm Recurrence, Local; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*