An Unusual Pattern of Hepatic Involvement in Plasma Cell Leukemia

Plasma cell leukemia (PCL) is a rare and aggressive plasma cell neoplasm associated with dismal outcomes. Organ involvement in PCL, including the spleen and the liver, is rare and commonly manifests as diffuse infiltration of neoplastic plasma cells. We report a patient with PCL, status post combination chemotherapy, identified to have hepatic lesions on positron emission tomography as part of a pre-bone marrow transplant workup. Biopsy of the hepatic mass revealed sheets of atypical plasma cells within the hepatic parenchyma. Immunohistochemical staining showed strong expression of CD138 and MUM1. In situ hybridization demonstrated lambda light chain restriction, confirming hepatic involvement of the patient's known PCL. The patient was subsequently recommended for second-line CAR-T therapy in lieu of the planned autologous transplant. This case demonstrates an unusual manifestation of PCL and the importance of maintaining a broad differential diagnosis for hepatic lesions in patients with aggressive plasma cell neoplasms due to its implications for accurate diagnosis and treatment planning.