Mobile Enlarging Scalp Nodule

Abstract

A 50-year-old man presented with a 2.5-cm, subcutaneous, freely mobile nodule on the occipital scalp that first appeared 35 years prior but recently had started enlarging. Histologically the lesion was well circumscribed. Immunohistochemical staining was positive for SRY-box transcription factor 10 in some of the spindle cells, and staining for epithelial membrane antigen was positive in a separate population of intermixed spindle cells. THE BEST DIAGNOSIS IS:a. desmoplastic melanoma b. hybrid schwannoma-perineurioma c. malignant peripheral nerve sheath tumor d. neurofibroma e. schwannoma