Multiple intradermal soft tissue perineuriomas of the digit

Perineurioma is a rare benign peripheral nerve sheath tumor, composed uniformly of perineurial cells. Soft tissue perineurioma primarily arises within the subcutaneous tissue of extremities and trunk as a painless solitary nodule, and should be distinguished from dermatofibroma, neurofibroma, dermatofibrosarcoma protuberans, meningioma and so on. A 25 year-old female is presented with three small asymptomatic papules on the third left finger which were found 3 years ago. Punch biopsy was performed on all of the papules. Microscopic examination demonstrated well-demarcated tumor within dermis, and proliferation of spindle cells with wavy nuclei and elongated bipolar cytoplasmic process, arranged in a whorled pattern. According to immunohistochemical analysis, the tumor cell showed positivity for epithelial membrane antigen, but negativity for S-100 protein, factor Xffla, CD34, and smooth muscle actin. The diagnosis of soft tissue perineurioma was being made. We report this rare case of perineurioma presented as multiple papules localized within dermis of the digit.