Authors : Sameer P Ahamed , Soumya B M, Vardendra Kulkarni
DOI : 10.18231/j.occ.2025.006
Volume : 3
Issue : 1
Year : 2025
Page No : 35-39
Pigmented neurofibroma (PNF) is an extremely rare variant of neurofibroma, often associated with neurofibromatosis type 1 (NF1). It can be mistaken for other pigmented soft tissue tumors, including pigmented dermatofibrosarcoma protuberans (DFSP), posing diagnostic challenges. We report a case of a 32-year-old male with a slow-growing gluteal mass of 20 years’ duration. The patient had no clinical signs or family history of NF1. The excised mass was examined grossly, histologically, and immunohistochemically. Gross examination revealed a 20×20×3 cm, poorly circumscribed, rubbery lesion with brown-black pigmentation. Histology showed a non-encapsulated spindle cell tumor arranged in interlacing bundles with pigmented dendritic and epithelioid cells and occasional Wagner-Meissner bodies. Immunohistochemistry revealed S100 positivity in both pigmented and spindle cells and CD34 expression restricted to the spindle cells. Differential diagnosis included pigmented DFSP, which was ruled out based on histology and immunostaining pattern. Giant isolated pigmented neurofibroma without NF1 stigmata is extremely rare. Recognition of key histological features and accurate immunohistochemical profiling is essential to differentiate it from more aggressive pigmented tumors such as DFSP or melanoma.