Fibrous meningioma with tyrosine-rich crystals

A 58-year-old African-American woman presented with a a-month history of he adaches. A magnetic resonance imaging scan of the head revealed a 5-cm, enh ancing dura-based mass in the left parietal region. The variably cellular t umor was composed of uniform spindle cells associated with intercellular co llagen and numerous radially arranged "petal-shaped" clusters of eosinophil ic crystals. The tumor was diagnosed by light microscopy as a fibrous menin gioma. Ultrastructural examination disclosed cells with complex interdigita ting processes connected by desmosome-like cell junctions, abundant interce llular collagen fibers, and prominent, densely osmiophilic crystals featuri ng radiating teardrop shaped petals emanating from a central core. A positi ve Millon reaction showed these crystals to consist at least in part of tyr osine. By morphology, histochemistry, and ultrastructure, the crystals rese mbled tyrosine-rich crystals occurring in salivary gland tumors. This is th e first report of a fibrous meningioma containing tyrosine-rich crystals.