Fibroblastic connective tissue nevus: Clinicopathological and immunohistochemical study of 14 cases

Summary

We present herein a series of 14 lesions showing overlapping features with the newly defined benign cutaneous mesenchymal neoplasm labelled as fibroblastic connective tissue nevus (FCTN). Eight patients were male and five were female, ranging in age from 1 to 56 years. Lesions appeared as isolated nodules or plaques on the trunk (7 cases), the limbs (4 cases) and the neck (2 cases). Histologically, all cases were composed of bundles of bland spindle cells of fibroblastic/myofibroblastic lineage irregularly branching within the reticular dermis and along fibrous septa in the subcutis. Adnexal structures and dermal adipocytes were entrapped by the fascicles, the epidermis was often papillomatous and elastic fibres were decreased and fragmented. Expression of CD34 and ASMA was found in 8 and 7 cases, respectively. Follow-up was available for 7 patients (mean follow-up, 5 y; range, 1 to 10y). None of the cases metastasized or recurred, even when incompletely excised.The differential diagnosis_of FCTN is broad and includes hypertrophic scar, dermatofibroma, dermatomyofibroma, pilar leiomyoma, plaque-stage DFSP, CD34-positive plaque-like dermal fibroma, fibroblastic predominant plexiform fibrohistiocytic tumor,_lipofibromatosis, superficial desmoid fibromatosis and fibrous hamartoma of infancy, of which it_represents probably the monophasic variant.