Abstract
Our patient is an 8-year-old female presenting with a one-year history of an asymptomatic papule on the nose. Examination revealed a 3 mm smooth, dome-shaped pink-brown papule at the nasal tip. The differential diagnosis included juvenile xanthogranuloma, Spitz nevus, atypical melanocytic nevus, or other less common dermal neoplasm. A shave biopsy performed for definitive diagnosis showed variable nests of medium-sized epithelioid cells within the dermis associated with myxoid stroma containing nests surrounded by dense dermal collagen. There was mild cellular pleomorphism without mitotic figures. The tissue stained positive for NKI/C3 (diffuse), MITF (nuclear), CD68 (cytoplasmic), and SMA (weak subset cytoplasmic) and negative for EMA, Melan-A, and S100. Given pathology consistent with cellular neurothekeoma (CNT), our patient was referred to plastic surgery for excision with 1-2 mm clinical margin. CNT is a benign neoplasm appearing predominantly as a solitary, asymptomatic red-brown papule on the head and neck of young, female patients. CNT, previously classified as a variant of a nerve sheath myxoma, is now recognized as an independent fibrohistiocytic entity. H&E shows a multinodular dermal mass of epithelioid and spindled cells with myxoid matrix and peripheral fibrosis. There is minimal to mild nuclear pleomorphism and mitotic figures. Immunostaining is generally positive for NKI-C3 and CD10, often positive for vimentin, micropthalmia transcription factor, PGP9.5, and occasionally positive for SMA and CD68. Staining for S100 and Melan-A are negative, differentiating CNT from a classic neurothekeoma. Dermatologists and dermatopathologists should consider CNT in the differential for a solitary dermal nodule in pediatric patients.