Cutaneous plexiform schwannoma associated with neurofibromatosis type 2.

Background: Plexiform schwannoma (PS) is a rare benign tumor of the nerve sheath that can be located either in the deep soft tissues or in the dermis or subcutis. The tumor predominantly affects young adults and occurs most commonly as a slowly growing asymptomatic solitary nodule in the head and neck region, trunk, and upper extremities.

Methods: A cutaneous PS located in the preauricular region of a 19-year-old white female is reported. The patient exhibited six "café-au-lait" spots in the trunk and the extremities. Magnetic resonance imaging examination showed bilateral tumors in both acoustic nerves (considered schwannomas) and also masses in the right major sphenoidal wing, falx, and T2-T3 level of rachis and a solid and cystic tumor in the low medulla oblongata. Tumors of the preauricular region, medulla oblongata, spinal cord at level T2-T3, and major sphenoidal wing area were surgically removed. The tumors were studied by immunohistochemistry and diagnosed as PS, pilocytic astrocytoma, and meningiomas, respectively.

Results: Seventy-eight cases of PS have been reported in the literature: 8 (10.2%) have been associated with clinical schwannomatosis, 6 (7.7%) with multiple cutaneous schwannomas syndrome, and only 3 (3.8%) with neurofibromatosis type 1 (NF-1).

Conclusions: In this report, to the authors' knowledge, for the first time PS is described associated with neurofibromatosis type 2. The tumor does not appear to have significant association with NF-1. Plexiform schwannoma should be recognized because it may be misdiagnosed as plexiform neurofibroma or other plexiform malignant tumors. Differentiation from plexiform neurofibroma is important, because the latter is virtually pathognomonic of neurofibromatosis type 1 and has a propensity for malignant transformation.