Calcifying amyloidoma of the breast.

In this case, a distinctive amyloid tumor of the breast clinically simulated carcinoma, although the patient related onset to trauma. Hepatosplenomegaly, elevated globulins, and anemia led to identification of large amounts of monoclonal IgG-kappa production. The patient died of renal failure within several months despite chemotherapy. The matrix of the breast tumor was tinctorially characteristic of amyloid light chain (AL) protein. The mass contained islands of plasma cells that morphologically suggested local production of amyloid matrix. Moreover, plasma cell and matrix immunohistochemically displayed reactivity of IgG-kappa protein, indicating a clonal plasma cell infiltrate. Pseudo-acinar arrangement of plasma cells may be misinterpreted as epithelial cells in needle biopsy specimens. The notion that some amyloidomas may represent in situ production of protein by clonal immunocytes ("secretory immunocytomas") should be further studied.