Spherulosis of the breast. A spectrum of municous and collagenous lesions.

Abstract

Collagenous spherulosis of the breast is an uncommon localized pattern of basement membrane material deposition that may be mistaken for atypical proliferations or carcinoma. This report describes 9 cases in which the predominant or exclusive appearance of the spherules was basophilic instead of eosinophilic. The files of all cases of collagenous spherulosis diagnosed at the Armed Forces Institute of Pathology were reviewed to ascertain the frequency of diagnosis. Spherulosis with a predominantly basophilic pattern had a histochemical and immunohistochemical profile similar to collagenous spherulosis and was associated with more collagenous-appearing forms in 7 of 9 cases. Review of 81 cases showed that collagenous spherulosis was correctly diagnosed in 15% of referrals and was mistaken for intraductal or invasive carcinoma in 11% of cases. Mucinous and collagenous patterns appear to be related forms of spherulosis. They are underrecognized by pathologists and maybe mistaken for atypia or malignancy.