A Case of Concomitant Multiple Myeloma and Cirrhosis.

A 66-year-old Caucasian female with a recent history of COVID-19 (about one month prior to the current admission) and cirrhosis, presented with acute kidney injury (AKI) and worsening encephalopathy. Initial management focused on addressing her AKI, initially suspected to be secondary to volume depletion or hepatorenal syndrome (HRS) and confusion from hepatic encephalopathy. However, further evaluation unveiled a persistent serum protein gap, hypercalcemia, and significant non-albumin proteinuria, prompting a more comprehensive diagnostic approach. Subsequent investigations revealed a high serum free light chain ratio, positive serum protein electrophoresis, and monoclonal gammopathy, indicative of a plasma cell disorder. A bone survey did not indicate aggressive bone lesions, but a bone marrow biopsy confirmed multiple myeloma with approximately 10% kappa light chain-restricted plasma cells. Despite appropriate treatment, the patient's health continued to decline, and the patient was subsequently transitioned to comfort care. While the relationship between cirrhosis and multiple myeloma remains to be fully understood, our case report explores four potential explanations: coincidental coexistence, cirrhosis as a risk factor for multiple myeloma, multiple myeloma as a risk factor for cirrhosis, or a shared predisposing condition.