Crystalline deposits in the cornea and various areas of the kidney as symptoms of an underlying monoclonal gammopathy: a case report

Abstract

Background Plasma cell dyscrasias (PCD) are characterized by an abnormal production of intact monoclonal immunoglobulins or parts such as heavy or light chains. In most cases, the monoclonal protein (also termed paraprotein) is produced by a clonal plasma cell population. The production of monoclonal proteins can result in deposits of various types and localization depending on the type, amount, and electrochemical properties of the paraprotein. One histopathologic presentation, albeit rare, are crystalline deposits. They can form in various organs and hence cause a wide spectrum of symptoms. Case presentation A 49-year-old man presented to the emergency department with eyestrain and foreign body sensation after overhead drilling. Examination of the eyes revealed crystalline deposits in the cornea of both eyes. After additional diagnostic testing, deposits were attributed to free light chains. Monoclonal gammopathy of undetermined significance (MGUS) was diagnosed according to serum electrophoresis and immunofixation. Four years later, new onset of proteinuria was detected. A percutaneous biopsy of the kidney showed severe light chain podocytopathy with secondary focal segmental glomerulosclerosis (FSGS) and light chain proximal tubulopathy (LCPT). In these lesions, crystalline deposits identical to the corneal deposits were found in ultrastructural and immunofluorescent analysis. The patient was diagnosed with monoclonal gammopathy of renal significance (MGRS), and a plasma cell directed therapy was initiated. Conclusions PCD can present with a wide array of symptoms and are notoriously difficult to diagnose. Extrarenal manifestations such as crystalline deposits in the cornea are one possible manifestation. The case presented herein emphasizes the notion that extrarenal paraprotein deposits warrant a thorough search for the underlying clonal disease.

Monoclonal Light Chains in Multiple Myeloma: The Sinister Immunoglobulin

“…The systemic significance of monoclonal light chain-induced vasculitis and thrombotic microangiopathy warrants additional investigation, as generalized vasculitis has the potential to damage other vital organs as well [16,[55][56][57][58][59][60][61][62][63][64]. Uncommon disorders include light chain renal stones, light chain crystal deposition in cornea, skeletal myopathy, pulmonary embolism, acquired cutis laxa, cutaneous light chain deposition disease, cholestasic hepatitis and light chain deposition liver disease [65][66][67][68][69][70].…”

Paraproteinemic keratopathy: recognizing the ocular significance

“…Keratopathy may develop years before other endorgan damage and may present an opportunity for early intervention. 8 Ocular symptoms are not yet an indication for systemic therapy of paraproteinemic keratopathy, even when the ocular disease is sight threatening and affects activities of daily living. Currently, cases of isolated paraproteinemic keratopathy are classified as monoclonal gammopathy end-organ 6 We instead support the use of monoclonal gammopathy of ocular significance, suggested by Karakus et al 4 and Nobacht et al, 2 which reflects the significant visual impairment that may result.…”