Schwannomatosis is a genetic disorder characterized by the occurrence of multiple peripheral schwannomas. Segmental schwannomatosis is diagnosed when schwannomas are restricted to one extremity and is thought to be caused by genetic mosaicism. We studied five patients with segmental schwannomatosis through microstructural magnetic resonance neurography and mutation analysis of NF2, SMARCB1, and LZTR1. In four of five patients subtle fascicular nerve lesions were detected in clinically unaffected extremities. Two patients exhibited LZTR1 germline mutations. This appears contrary to a simple concept of genetic mosaicism and suggests more complex and heterogeneous mechanisms underlying the phenotype of segmental schwannomatosis than previously thought. This article is protected by copyright. All rights reserved.
