title: Mucinous carcinoma occurring in the male breast.
abstract: Male breast carcinoma is an uncommon neoplasm, accounting for 0.6% of all breast carcinomas. Invasive ductal carcinoma of no special type is the most common type of male breast carcinoma, and mucinous carcinoma occurring in the male breast is extremely rare. In the present study, we report a case of mucinous carcinoma of the male breast and discuss the clinicopathological features of this type of tumor. A 63-year-old Japanese male presented with a gradually enlarged nodule in the right breast. The resected breast specimen revealed pure mucinous carcinoma and immunohistochemical analyses demonstrated that tumor cells were positive for estrogen receptor (ER), but negative for progesterone receptor (PgR). In addition, HER2 expression was not amplified. Pure mucinous carcinoma is generally associated with a low incidence of lymph node or distant metastases, and excellent disease-free survival in females. However, certain cases of this type of tumor with axillary lymph node metastasis in the male breast have been reported. In addition, the immunoprofiles of mucinous carcinoma in males are fundamentally the same as those in females. More than 90% of cases show positive immunoreactivity for ER and/or PgR, and HER2 expression is not amplified. However, it has been reported that breast cancer in males is more frequently positive for ER than in females, and has less HER2 overexpression. The high rate of hormone receptor-positive breast cancer in males is considered to be due to similar conditions as those in breast cancer in postmenopausal women. The pathogenesis of male breast carcinoma, including mucinous carcinoma, remains unclear; therefore, additional clinicopathological studies are required.
authors.affiliation: Department of Clinical Laboratory Medicine and Division of Diagnostic Pathology, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Ishida
authors.affiliation: Department of Surgery, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Umeda
authors.affiliation: Department of Surgery, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kawai
authors.affiliation: Department of Surgery, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Mori
authors.affiliation: Department of Surgery, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kubota
authors.affiliation: Department of Surgery, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Abe
authors.affiliation: Department of Clinical Laboratory Medicine and Division of Diagnostic Pathology, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
authors.forename: Muneo
authors.initials: M
authors.lastname: Iwai
authors.affiliation: Department of Clinical Laboratory Medicine and Division of Diagnostic Pathology, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Department of Clinical Laboratory Medicine and Division of Diagnostic Pathology, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Kagotani
authors.affiliation: Department of Surgery, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Tani
authors.affiliation: Department of Clinical Laboratory Medicine and Division of Diagnostic Pathology, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Okabe
keywords: estrogen receptor; male breast; mucinous carcinoma