Cutaneous neuroblastoma-like schwannoma: a report of two cases, one with a plexiform pattern, and a review of the literature.

Cutaneous schwannomas in their classical form are readily identified histologically. A number of variants, including ancient, cellular, epithelioid, plexiform, microcystic and neuroblastoma-like, may cause diagnostic difficulty and rarely be confused with malignancy. Neuroblastoma-like schwannoma was first described by Goldblum et al. in 1994, and very few cases have since been reported. It is a benign sporadic neoplasm with no reported association with neurofibromatosis, and is characterized histologically by small round lesional cells surrounding collagenous cores forming rosette-like structures. The differential diagnosis includes other lesions with the formation of rosettes including neuroblastoma, low-grade fibromyxoid sarcoma and dendritic cell neurofibroma, as well as primitive neuroectodermal tumors and rare malignant transformation in a schwannoma. We describe two further cases of this rare entity and review the literature on the subject. Our first case additionally has a plexiform multinodular pattern, a feature described in only one previous report.