Crystalline light-chain deposition and amyloidosis in the thyroid gland and kidneys of a patient with myeloma.

A 48-year-old Japanese woman died of multiple myeloma (lambda light-chain type) with chronic renal failure. Histological examination revealed deposition of a homogeneous substance and crystals in the kidneys and thyroid gland. The homogeneous substance was stained with Congo red after permanganate treatment but did not stain with antibody to amyloid A protein, and it was recognized as AL-type amyloid. Crystals were not stained with Congo red, but crystals were stained with antibody to the lambda light chain. Since AL-type amyloid is considered to be derived from a myeloma light chain, the present case showed two different types of deposition, both of which were derived from the same myeloma protein.