Collagenous spherulosis: An interesting cytological finding in breast lesion

Collagenous spherulosis (CS) is a rare and interesting entity associated with benign breast lesions. CS is an incidental finding picked up only on 0.2% of cytology specimen. Typically cytologically of CS of breast consists of central spherical hyaline spherule surrounded by myoepithelial cells. The central hyaline spherule has been found to be basement membrane material histochemically and immunohistochemically. The importance of recognizing CS of breast lies in the fact that similar hyaline globules can occur in adenoid cystic carcinoma of the breast (ACCB). The two lesions need to be differentiated on cytology failing which inappropriate treatment can be given for either of the two lesions. We present here a case of CS associated with benign breast lesion and a case of ACCB to describe their cytological features and key points to differentiate them cytologically.