Widespread crystallisation of paraprotein in myelomatosis.

Two patients with myelomatosis leading to acute renal failure were found at autopsy to have extensive crystalline deposits of paraprotein within the capsular space of the glomeruli, renal tubules and renal blood vessels. In one case, crystalline deposits in the renal arteries had caused infarction of both kidneys. Both patients had extensive paraprotein deposits in the heart and in other tissues, leading to myocardial infarction in one case. This patient also had extensive pulmonary deposits of paraprotein without a local plasma cell infiltrate, an appearance which has not been described before. Crystalline deposition does not appear to be specifically associated with a single class of paraprotein. This type of disease, affecting many organs, may be more common than has generally been appreciated and should be considered as a cause of otherwise unexplained organ failure in patients with myelomatosis.