Encapsulated papillary carcinoma associated with mucinous carcinoma in the male breast: a case report
Year: 2026
Type: article
Study design: Case Report
Abstract: Introduction and importance: Male breast cancer is rare, accounting for less than 1% of breast cancer cases. The coexistence of encapsulated papillary carcinoma (EPC) and mucinous carcinoma in the same male breast is exceptionally rare. Case presentation: A 55-year-old man presented with a long-standing right breast mass. Imaging revealed a subareolar lesion classified as BI-RADS 4C. Histologically, two adjacent tumors separated by a thin fibrous band showed the characteristic features of mucinous carcinoma and EPC. Myoepithelial markers (p63 and SMMS1) were absent within the papillae and at the tumor periphery, supporting EPC. Both components were estrogen receptor- and progesterone receptor-positive and human epidermal growth factor receptor 2-negative, with a low Ki-67 index. No lymph node metastasis was identified (pT2N0). Clinical discussion: The coexistence of EPC and mucinous carcinoma in the same male breast is extremely rare and, to our knowledge, has not been previously reported. The distinct histopathological features and immunohistochemical profiles of the two components support their classification as separate tumor entities. However, their close anatomical association raises the possibility of a common neoplastic origin, although the precise histogenetic relationship remains uncertain. Conclusion: This case highlights the diagnostic complexity of this rare tumor combination and the importance of careful morphological and immunohistochemical evaluation.
Author: Vimpattra Tragoolwananon
Institution: ChiangRai Prachanukroh Hospital
Language: English
Topic: Male Breast Health Studies
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,090
OpenAlex ID: W7225705233