A 4-month-old infant presented with asymptomatic soft nodules on his right forearm, which had developed since birth. On the suspicion of nevus lipomatosus superficialis (NLS), biopsy was performed. Histopathologic findings showed monomorphic polygonal cells with abundant granular cytoplasm. Immunohistochemical stains for CD68 and vimentin were strongly positive, but were negative for S-100 protein. Based on the pathologic findings, the patient was diagnosed as non-neural granular cell tumor (NN-GCT). GCT can be divided into conventional and non-neural GCT by immunoreactivity for S-100 protein. NN-GCT is typically manifested as a well-circumscribed, papulo-nodular dermal mass, and is known to occur in a younger group than does in conventional GCT, but is rare among children. To our knowledge, there have been no case reports of NN-GCT which appeared at birth and presented as grouped nodules. Therefore, we report this interesting case of congenital NN-GCT clinically mimicking NLS.
Keywords: CD68; Granular cell tumor; Nevus lipomatosus superficialis; S100 proteins; Vimentin.