Histochemical study of the masseter muscle. A case of hypertrophic masseter myopathy.

Hypertrophy of the masseter muscle is a relatively uncommon condition which may occur unilaterally or bilaterally. The etiology is unclear in most cases.A case of unilateral masseteric hypertrophy in a 17-year-old girl was described. Histochemical study was performed and features of the masseter muscle were compatible with a myopathic disorder, uniform type 1 fiber and gross hypertrophy of type 1 fibers.This disorder was termed branchial hypertrophic myopathy or hypertrophic masseter myopathy because it was confined to the masseter muscle.