Plasma cell acid phosphatase, a discriminative test for benign and malignant monoclonal gammopathies.

Acid phosphatase activity estimated cytochemically is markedly increased in myeloma plasma cells compared to that found in normal plasma cells, polyclonal plasma-cytoses and most interestingly in the non-myelomatous monoclonal dysglobulinaemias. In the differential diagnosis of this last group the test has a useful role.