Posterior corneal crystalline deposits in benign monoclonal gammopathy: a clinicopathologic case report.

A 74-year-old woman had bilateral, deep stromal, patchy crystalline corneal deposits with the greatest density in the midperiphery. Visual acuity was 6/120 in the right eye and finger counting at 1 m in the left eye. Histological examination of the corneal button showed large, irregular amorphous masses in the posterior stroma. The deposits stained red with Masson's trichrome and were positive for protein with the Danielli stain. Stains for amyloid, copper, and lipid were negative. The immunoperoxidase stain was positive for polyvalent IgG and kappa light chains. Transmission electron microscopy disclosed electron-dense deposits with linear and honeycomb profiles. Laboratory investigations disclosed elevated serum and urinary IgG kappa light chain (Bence Jones protein) levels. Urinary amino acids were normal. The serum copper level was elevated. Antinuclear antibody was positive at a titer of 1:80. A bone marrow aspirate was normal, as were roentgenograms of the skull.