Mononeuropathy multiplex as the initial manifestation of neurofibromatosis type 2

The authors report a patient with neurofibromatosis type 2 (NF2) presenting with an axonal mononeuropathy multiplex. Sural nerve biopsy showed small scattered groups of Schwann cells transformed into irregular branching cells with abnormal cell-cell contacts. The authors hypothesize that defective Schwann cell function, due to inactivation of the NF2 gene product merlin, leads to changes in morphology, cell-cell contact, and growth, and finally to degeneration of axons.