Paraproteinemic keratopathy in monoclonal gammopathy of undetermined significance treated with primary keratoprosthesis: Case report, histopathologic findings, and world literature review.

Rationale: We report a case of paraproteinemic keratopathy associated with monoclonal gammopathy of undetermined significance, treated with keratoprosthesis as a primary penetrating procedure. Histopathological findings and a world literature review are presented. Patient concerns: A 74 year old female recently diagnosed with monoclonal gammopathy undetermined significance presented with progressive blurry vision bilaterally. Diagnoses: Examination revealed corneal opacities consistent with paraproteinemic keratopathy. Interventions: Corneal transplantation with the Boston Type I keratoprosthesis was performed on the right and, a year later, on the left. Outcomes: Visual outcomes were good. Histopathological staining of host corneal buttons were consistent with monoclonality, and electron microscopy revealed fibrillar extracellular aggregates within intervening normal stroma. Lessons: Corneal deposits may be the only manifestation of monoclonal gammopathy of undetermined significance in patients who are otherwise systemically asymptomatic. Ophthalmologists who encounter corneal opacities may order the appropriate diagnostic studies to determine the presence of occult systemic disease. Risk of graft failure after penetrating keratoplasty from recurring opacities is high, so keratoprosthesis as a primary penetrating procedure mayafford superior long-term outcomes. Host corneal buttons retrieved from penetrating keratoplasty or corneal biopsy may be sent for histopathological examination to confirm the diagnosis.