Corneal crystalline deposits associated with dysproteinemia. Report of two cases and review of the literature.

Two patients had multiple, fine, polychromatic corneal crystals on ocular examination. Peripheral corneal biopsies and electron microscopic studies demonstrated that the crystals, which were located solely within the cytoplasm of keratocytes, exhibited an internal periodicity of 10 nm and developed within dilated cisternae of rough-surfaced endoplasmic reticulum. Histochemical studies of the corneal crystals confirmed their proteinaceous nature (immunoglobulin crystals). Serum protein analysis showed that both patients had a monoclonal gammopathy with an elevated IgG level and increased K light chains. The associated proteinopathy was unsuspected in both patients until the nature of the crystals was established. Both patients had a neoplastic process; one had a previous diagnosis of Hodgkin's disease, and multiple myeloma developed in the other on follow-up studies. Clinicians should be aware of the possibility of a malignant disorder in patients with corneal crystal-line deposits.