Plasmacytic conjunctivitis with crystalline inclusions. Immunohistochemical and ultrastructural studies

A 17-year-old girl had bilateral papillary conjunctivitis. Histologically, the lesion showed mature plasmacytes, plasmacytoid cells, and large mononuclear cells that exhibited myriad intracytoplasmic crystals. Electron microscopic studies disclosed that the large mononuclear cells, which showed plasmacytic differentiation, contained numerous crystalline inclusions. The crystals were formed within the rough-surfaced endoplasmic reticulum and exhibited a regular periodicity (8 nm). Histochemical methods disclosed that the composition of the crystals was mainly protein (immunoglobulin crystals). Immunoperoxidase techniques for demonstration of immunoglobulins showed that the crystalline inclusions contained IgG. The results of immunohistochemical findings correlated with the results of immunoelectrophoresis of the patient's serum.