Clinical Features and Treatment Response of Light Chain (AL) Amyloidosis Diagnosed in Patients With Previous Diagnosis of Multiple Myeloma

OBJECTIVE To identify and assess the clinical features and treatment response of light chain (AL) amyloidosis diagnosed in patients with previous diagnosis of multiple myeloma (MM). PATIENTS AND METHODS From a prospectively maintained database, we identified 47 patients seen between January 1, 1990. and August 31, 2008, with a diagnosis of AL amyloidosis that was made at least 6 months after MM diagnosis; these patients form the study group. RESULTS Among the 47 patients, 36 developed typical features, 3 had atypical features, and 8 had an incidental finding of amyloidosis. Amyloid deposits were demonstrated in bone marrow, subcutaneous fat aspirate, or organ biopsy in 24, 19, and 12 patients, respectively. One organ was involved In 29 patients (62%), whereas 11 patients (23%) had involvement in more than one organ. At diagnosis of AL amyloidosis, treatment was changed or started in 22 patients, whereas the same treatment was continued in 21 patients, and no treatment data were available for the rest. The best hematologic response included partial response or better in 11 patients (23%) and stable disease in 18 patients (38%). Improvement in an organ was seen in 3 of the 21 evaluable patients. The median overall survival from diagnosis of AL amyloidosis was 9.1 months (95% confidence interval, 4-14). Of the 6 patients still alive, 2 underwent peripheral blood stem cell transplant, and none had cardiac involvement or involvement in more than one organ. CONCLUSION Delayed onset of AL amyloidosis is rarely seen in patients with MM and requires a high index of suspicion for prompt diagnosis. Outcome of these patients is poor, especially in the presence of cardiac involvement.