When unilateral vestibular schwannoma is not due to neurofibromatosis

Revisiting neurofibromatosis type 2 diagnostic criteria to exclude LZTR1-related schwannomatosis.

Smith MJ, Bowers NL, Bulman M, et al.

Neurology 2017; 88:87-92.

Abstract

OBJECTIVE:

To determine the specificity of the current clinical diagnostic criteria for neurofibromatosis type 2 (NF2) relative to the requirement for unilateral vestibular schwannoma (VS) and at least 2 other NF2-related tumors.

METHODS:

We interrogated our Manchester NF2 database, which contained 205 individuals meeting NF2 criteria who initially presented with a unilateral VS. Of these, 83 (40.7%) went on to develop a contralateral VS. We concentrated our genetic analysis on a group of 70 who initially fulfilled NF2 criteria with a unilateral vestibular schwannoma and at least 2 additional nonintradermal schwannomas.

RESULTS:

Overall, 5/70 (7%) individuals with unilateral VS and at least 2 other schwannomas had a pathogenic or likely pathogenic LZTR1 mutation. Twenty of the 70 subsequently developed bilateral disease. Of the remaining 50, 5 (10%) had a germline LZTR1 mutation, equivalent to the number (n = 5) with a germline NF2 mutation.

CONCLUSIONS:

The most common etiology for unilateral VS and 2 additional NF2-associated tumors in this cohort was mosaic NF2. Germline LZTR1 and germline NF2 mutations were equally common in our cohort. This indicates that LZTR1 must be considered when making a diagnosis of NF2 in the presence of unilateral VS in individuals without a germline NF2 mutation.

This reference is now included in the neurochecklist:

Neurofibromatosis type 2 (NF2): clinical features

screen-shot-2016-12-24-at-23-32-53

Abstract link

By RadsWiki - RadsWiki, CC BY-SA 3.0, Link
By RadsWiki – RadsWiki, CC BY-SA 3.0, Link

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