Hepatic-Predominant Immunoglobulin G Lambda Light Chain Amyloidosis Associated With Multiple Myeloma: A Report of an Exceptionally Rare Case.

Amyloid light chain (AL) amyloidosis represents a rare plasma cell dyscrasia characterized by the deposition of misfolded immunoglobulin light chains in various organs. While hepatic involvement is often detected histologically in systemic AL amyloidosis, symptomatic hepatic presentation as the dominant initial manifestation remains uncommon. We present the case of a 65-year-old woman who developed progressive constitutional symptoms, cholestatic jaundice, and hepatomegaly as the initial manifestations of immunoglobulin G (IgG) lambda light chain amyloidosis associated with multiple myeloma. The patient presented with a six-month history of weight loss exceeding 20 kilograms, daily vomiting, night sweats, and progressive jaundice. Laboratory investigations revealed marked cholestasis, with an alkaline phosphatase level of 1252 U/L, a gamma-glutamyl transferase level of 1426 U/L, hyperbilirubinemia, and coagulopathy. Serum immunofixation electrophoresis demonstrated an IgG lambda monoclonal protein (M-protein). Abdominal fat pad biopsy confirmed lambda light chain amyloid deposition, while bone marrow examination revealed 30% plasma cell infiltration consistent with multiple myeloma. Echocardiography demonstrated findings suggestive of cardiac involvement with reduced global longitudinal strain and apical sparing pattern. Notably, renal function remained preserved without proteinuria, and skeletal imaging showed no lytic lesions. The patient was treated with daratumumab in combination with cyclophosphamide, bortezomib, and dexamethasone (Dara-VCD), demonstrating a very good partial response (VGPR) with 75% reduction of M-protein (from 1.2 g/L to 0.3 g/L) after four treatment cycles. This case exemplifies a clinically significant presentation combining IgG lambda-type multiple myeloma, systemic AL amyloidosis, and dominant hepatic involvement as the initial clinical manifestation. The combination of these features is rarely reported in the medical literature, making this case instructive for recognizing atypical presentations that may lead to diagnostic delays. Early recognition and prompt initiation of plasma cell-directed therapy are essential for improving outcomes in this challenging condition.