title: Gynecomastia with unusual intraductal "clear cell" changes mimicking pagetoid ductal spread of lobular neoplasia.
abstract: This report describes a case of unusual intraductal "clear cell" changes of male breast that mimicked pagetoid ductal spread of lobular neoplasia. The lesion developed inside a nodule of gynecomastia of the left breast in a 56 year-old man. Immunohistochemically, the enlarged clear cells reacted positively with epithelial membrane antigen, low molecular weight cytokeratin and three breast markers (i.e.: gross cystic disease fluid protein-15 and -44 and estrogen receptors). They were negative for high molecular weight cytokeratin, muscle-specific actin, desmin and vimentin. Differential diagnoses included pagetoid ductal involvement by lobular neoplasia (i.e.: lobular carcinoma in situ and/or atypical lobular hyperplasia), pagetoid growth of intraductal carcinoma, atypical intraductal hyperplasia, and unusual intraductal myoepithelial proliferative lesion.
authors.affiliation: University Institute of Pathology, Lausanne, Switzerland.
authors.forename: L
authors.initials: L
authors.lastname: Guillou
authors.forename: S
authors.initials: S
authors.lastname: Gebhard
mesh_terms: D003937:Diagnosis, Differential; D006177:Gynecomastia / Q000175:diagnosis / Q000473:pathology*; D006801:Humans; D006965:Hyperplasia / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010144:Paget's Disease, Mammary / Q000175:diagnosis / Q000473:pathology*