Cytogenetic evidence of clonality in cutaneous benign fibrous histiocytomas: a report of the CHAMP Study Group

Aims: Cutaneous benign fibrohistiocytic tumours are among the most common s oft tissue lesions. Their biological nature, in particular whether they are neoplastic or reactive, has long been disputed. Some morphological subtype s can be confused with sarcoma. Since available karyotypic data in these le sions are scarce, this study was undertaken to determine whether their cyto genetic analysis might demonstrate clonality and might help in differential diagnosis. Methods and results: Thirteen karyotyped benign cutaneous fibrous histiocyt omas (BFH) were morphologically reassessed and classified as ordinary BFH ( eight cases), cellular BFH (four cases), and one ankle-type lesion. Five ca ses (38%) showed clonal cytogenetic changes, although the aberrations varie d and did not correlate with histological subtypes. Karyotypic aberrations were more common in cellular BFH (3/4) than in the ordinary BFH (2/8). Conclusions: The demonstration of clonal chromosome abnormalities, in at le ast some cases, supports the neoplastic nature of cutaneous BFH. The karyot ypic changes identified are different from those in dermatofibrosarcoma, wi th which cellular BFH is often confused histologically.