Clinicopathological features of encapsulated papillary carcinoma of male breast

LI Simin; YUAN Jingping; YAN Honglin; LIU Lin; LUO Bin; RAO Jie

doi:10.3969/j.issn.1007-8096.2025.10.007

Abstract：Objective To investigate the clinical manifestations,histopathological features,diagnosis,and differential diagnosis of male breast encapsulated papillary carcinoma(EPC).Methods Clinical data of two cases of male breast EPC were collected.Their clinicopathological characteristics and immunophenotype were analyzed,and relevant literature was reviewed to summarize the characteristics of this disease.Results Both cases were male patients.Breast cystic-solid masses were detected by ultrasound,and intraoperative pathological examination confirmed breast carcinoma.One patient underwent left simple mastectomy with left axillary sentinel lymph node biopsy,while the other received left simple mastectomy alone.Grossly,the masses showed single cystic-solid tumors,with papillary structures visible in the cystic cavities.The main components of the tumors included a thick fibrous cyst wall and delicate papillary structures devoid of myoepithelial cells.Immunohistochemical results revealed that the tumor cells were strongly positive for estrogen receptor(ER)and progesterone receptor(PR),with a 1+immunoreactivity score for HER2.Staining for CK5/6 and p63 showed a complete absence of myoepithelial cells in both the papillary cores and the periphery of the tumor.Ki-67 proliferation index ranged from 10%to 20%.One patient received adjuvant chemotherapy and was followed up for 4 months,with no recurrence or distant metastasis observed.Conclusion EPC of the male breast is extremely rare and it is classified as an indolent malignant tumor.Surgical resection is the mainstay of treatment,and the prognosis is generally favorable.