Primary systemic amyloidosis with delayed progression to multiple myeloma.

BACKGROUND: Primary systemic amyloidosis (AL) and multiple myeloma both are clonal plasma cell proliferative disorders. Although 10-15% of patients with myeloma have coexisting primary amyloidosis, it is unusual for patients with primary amyloidosis to progress to myeloma at a later date. The authors describe a case series of six patients in whom such progression occurred.
METHODS: A computerized search was done of the medical records of all patients seen at the Mayo Clinic between January 1, 1960 and December 31, 1994 with a diagnosis of AL. Of 1596 patients with AL, 6 patients (age range, 60-74 years; median age, 68 years) with biopsy-proven AL were reviewed in whom delayed (at least 6 months after the diagnosis of AL) progression to multiple myeloma occurred.
RESULTS: At the time of the diagnosis of AL, none of the six patients had evidence of multiple myeloma. The dominant manifestation of AL was peripheral neuropathy in three patients and cutaneous AL, renal AL, and amyloid arthropathy in one patient each. The diagnosis of multiple myeloma was made 10-81 months after the diagnosis of AL, based on the demonstration of multiple osteolytic lesions (4 patients) or marked bone marrow infiltration (> or = 50%) by plasma cells (5 patients). Two patients had received chemotherapy (melphalan and prednisone) for AL. Five patients received chemotherapy (four patients) or high dose methylprednisolone (one patient) after the diagnosis of multiple myeloma. Five patients died, and the median actuarial survival after the diagnosis of multiple myeloma was 20 months. Multiple myeloma was the cause of death in four patients; one patient died of systemic amyloidosis. In 2 patients death occurred within 3 months.
CONCLUSIONS: AL occasionally progresses to overt multiple myeloma. These cases usually occur in patients without significant cardiac or hepatic AL who live long enough to develop multiple myeloma.