Unusual Presentation of Multiple Myeloma as a Liver Tumor at Initial Diagnosis: A Case Report

BACKGROUND Multiple myeloma (MM) is a hematologic cancer marked by malignant plasma cells in the bone marrow, often leading to bone pain, anemia, and renal issues. Rarely, MM presents as extramedullary myeloma in organs such as the liver, and is associated with a poor prognosis. CASE REPORT We report a 64-year-old woman with a history of aortic stenosis and transient ischemic attack who presented with severe anemia, epistaxis, and fatigue. Initial test results showed elevated liver enzymes, hypercalcemia, and kidney injury, with imaging revealing suspected liver metastases. Cancer markers, such as carcinoembryonic antigen, cancer antigen 15-3, and cancer antigen 125 were elevated. Liver biopsy showed plasma cells positive for CD138, CD38, and CD56, confirming MM. Additional tests found IgA kappa monoclonal proteins and 60% plasma cells in bone marrow, without bone lesions. The patient required an extended hospital stay, due to recurrent pleural effusions, hypercalcemia, and cholangitis requiring stent placement. After recovery from complications, including COVID-19, she was treated with 7 cycles of daratumumab-dexamethasone-lenalidomide and was scheduled for an autologous stem cell transplant. After 4 months of treatment, the patient had positive clinical outcomes in myeloma parameters and liver lesions. The patient had improved hemoglobin, white blood cells, neutrophils, and platelets. The patient's IgA decreased, hepatic enzymes improved, monoclonal protein bands disappeared, and liver lesions resolved. CONCLUSIONS This case highlights an uncommon MM presentation with liver involvement, underscoring the importance of considering MM in the differential diagnosis of atypical liver lesions and of early identification to improve treatment outcomes.