Lobular carcinoma of the male breast is very rare, because of the absence of lobules in the normal male breast.
Herein, a case of lobular carcinoma of the male breast with cellular features of signet ring cells is described. A 57-year-old man presented with a left breast mass.
Histologic examination showed classic invasive lobular carcinoma with in situ component. Most infiltrating tumor cells had a prominent signet ring cell appearance. The patient was phenotypically male and had fathered children.
There was no history of predisposing factors to breast lesion, such as hormone use or gynecomastia.