Cystic encapsulated papillary carcinoma with ductal carcinoma in situ in the male breast: a clinicopathologic feature with a diagnostic challenge: A case report and review of literature.

Rationale: Encapsulated papillary carcinoma (EPC) is a rare subset of breast carcinoma accounting for 0.5% to 2.0% of all patients with breast cancer and occuring mostly in postmenopausal women. It is even rarer in male breast cancer, and male EPC has only been reported in few cases. EPC has a distinctive histological pattern and a better prognosis compared with other types of breast carcinoma. Compared to the previously reported EPC cases, the lesion was unusually cystic made the diagnosis challenging. Accordingly, herein, we describe a rare case of EPC was unusually cystic in an elder male breast, associated with ductal carcinoma in situ (DCIS), along with an indepth literature discussion, and then to improve our understanding more about this uncommon tumor and further to provide more experience to treat this disease.

Patient Concerns: A 73-year-old man noticed a slowly enlarging mass in the right breast 1 year ago and sought medical attention. The patient presented with a right breast mass of 1-year duration and bloody nipple discharge in the first couple of days. The medical history was unremarkable.

Diagnoses: Physical examination, an elastic hard, smooth and movable 4-cm lesion was palpated below the right papilla. On the sonography, a well-defined predominantly cystic-solid tumor of 3.6 × 2.3 cm was confirmed. Postoperative pathological and immunohistochemical examinations of the surgical specimens revealed a final diagnosis of breast EPC with DCIS.

Interventions: The patient underwent surgery. A diagnosis of "a little papillary neoplasm of the breast with epithelial atypia and hypertrophy in the fibrous cystic wall" was made by the frozen section. Further, total mastectomy was performed.

Outcomes: The operation was successful. Then the male patient recovered completely, did not require any additional treatment and continued to do well on postsurgical mammary surgical clinic visits. The patient had been followed-up regularly for 2 years after surgery; he did not experience any complications and remained disease-free.