Intraluminal crystalloids in breast carcinoma: Immunohistochemical, ultrastructural, and energy-dispersive X-ray element analysis in four cases

Objective. - Intraluminal crystalloids have been described in the prostate, salivary gland, and ovary, but have not yet been reported in the breast. We report four cases of breast carcinoma in which these crystalloids were found in ducts with intraductal carcinoma or atypical hyperplasia. The presence of intraluminal crystalloids may be a useful adjunct in making a diagnosis of carcinoma or may be a feature to look for as a marker for the presence of carcinoma. Design. - Four cases of breast carcinoma containing intraluminal crystalloids were identified among 6900 surgical breast specimens between January 1990 and June 1995 at M.D. Anderson Cancer Center, Houston, Tex. Those sections with crystalloids identified by hematoxylin- eosin stain were stained with periodic acid-Schiff, Alcian blue, and mucicarmine stains. Immunohistochemical and ultrastructural studies and energy-dispersive x-ray analysis were also performed on these sections. Results. - The intraluminal crystalloids were eosinophilic, varied in shape and size, and did not exhibit birefringence under polarized light. Immunohistochemically, the crystalloids were negative for keratin, muscle- specific actin, and κ and λ light chains, but the surfaces stained positively for epithelial membrane antigen. By electron microscopy, the crystalloids had no limiting membrane and were composed of an electron-dense material with no discernible periodicity. By energy-dispersive x-ray element analysis, the crystalloids had no mineral content; however, sulfur was found, indicating a protein content. Conclusions. - The pathogenesis and constituents of these intraluminal crystalloids remain to be determined. Inasmuch as intraluminal crystalloids have not been found in normal ducts or acini, or in ductal hyperplasia without atypia, their presence may serve as a marker for breast carcinoma.