Unusual Presentation of IgD Lambda Multiple Myeloma with Femoral Head Amyloidosis: A Case Report and Literature Review.

IgD Multiple Myeloma accounts only for 2% of all Multiple Myeloma cases. It has been associated with various conditions and with complications involving many organs. The prognosis for IgD Multiple Myeloma is poor. This case report describes how a patient was diagnosed as IgD Lambda Multiple Myeloma complicated with left femoral head Amyloidosis. Initially, this 71 years old male patient presented with worsening left hip pain, reduced appetite, and weight loss for six months. Laboratory data showed chronic anemia, hypercalcemia, and acute renal failure. Bone marrow biopsy demonstrated sheets of plasma cells with abnormal nuclei. The initial routine serum immunofixation did not show any elevation of Immunoglobulins; and instead, noted decreased immunoglobulin level. Because of this unusual pattern of low Ig G, A, and M level, further work up on IgD investigation was pursued. Serum IgD workup showed a peak of 71 mg/dl and the urine immunofixation also demonstrated large amount of free monoclonal Lambda light chain. Finally, a left total hip arthroplasty was done. Congo Red stain of left femoral head biopsy revealed amyloidosis. This case illustrates association of IgD myeloma with amyloidosis. At the same time, it could easily be misdiagnosed as light chain disease if IgD abnormality was not carefully considered as a differential diagnosis. In addition, a concise review on IgD Multiple Myeloma is given.