[Transformation of a rib plasmocytoma into an amyloid tumor (author's transl)]

The appearance of amyloidosis during the course of multiple myeloma is a well known fact and has an overall incidence of 6 to 15%. However, the total transformation of a plasmocytoma into a voluminous amyloid tumor is a very rare event. A female patient was diagnosed of lambda light chain disease after developing a conspicuous rib plasmocytoma over the same region where a pathological fracture had appeared three years before. She was treated with discontinuous courses of melphalan and methyl-prednisolone, and developed a reversible nephrotic syndrome and a pathological fracture of the right clavicle. At necropsy there was generalized amyloidosis and complete substitution of the rib plasmocytoma by amyloid substance, with another important accumulation of amyloid in the region of the clavicular fracture. The present concepts on amyloidogenesis in multiple myeloma are reviewed, and the peculiarities of the present case together with the possible role of initiating factors and the effects of therapy are discussed. The case herein reported appears to represent a human model of focal amyloidogenesis in myeloma.