CUTANEOUS SCLEROTIC FIBROMA - IMMUNOHISTOCHEMICAL EVIDENCE OF A FIBROBLASTIC NEOPLASM WITH ONGOING TYPE-I COLLAGEN-SYNTHESIS

The sclerotic fibroma (SF) is a tumor of the skin that may occur spora dically or in the context of Cowden's syndrome. The authors studied fo ur examples of this tumor in an effort to understand better the nature of the fibrous matrix in SF and its significance. A novel antibody wa s utilized that is directed against the immunoreactive amino-terminal precuror domain of human type I procollagen (AP). This peptide is usua lly identified only at sites of active or recent collagen synthesis an d deposition. All examples of SF showed strong cellular and stromal st aining for AP. The matrix also demonstrated variable staining for type IV collagen and laminin. The overall immunophenotype of this lesion s uggests that it may be a specialized fibroblastic (''dermal dendrocyti c?'') tumor. Despite its hypocellularity and hyalinized nature, SF is thought to exhibit ongoing matrical production that supports a neoplas tic character for this lesion.