Encapsulated papillary carcinoma with and without frank invasion: Comparison of clinicopathologic features and role of axillary staging

Encapsulated Papillary Carcinoma of the Breast: A Review of Clinicopathologic Characteristics, Molecular Mechanisms, and Patient Management

Encapsulated papillary carcinoma (EPC) represents a distinct entity within the spectrum of breast papillary tumors, typically manifesting as a retroareolar mass. This rare subtype can be effectively visualized using ultrasound and magnetic resonance imaging, which reveal characteristic cystic-solid nodules. Histopathologically, EPC is defined by a papillary tumor structure with a well-defined fibrous capsule, devoid of myoepithelial cells both within and around the capsule. Immunohistochemical staining for myoepithelial markers is essential to confirm the absence of these cells, thereby validating the diagnosis of EPC. At the molecular level, EPC exhibits feature similar to estrogen receptor-positive invasive ductal carcinoma (IDC), with a biological behavior that lies between ductal carcinoma in situ (DCIS) and IDC. Generally, EPC has a favorable prognosis, associated with minimal recurrence and metastatic potential. Therapeutic strategies for EPC may parallel those for DCIS, including surgical excision. Adjuvant radiotherapy is recommended following surgery for patients with concurrent DCIS or those who have undergone breast-conserving therapy. In cases with associated IDC, management prioritizes the treatment of the invasive component. High-grade EPC often requires systemic therapies due to its poorer prognosis and increased risk of lymph node involvement.

Oncological outcomes for encapsulated papillary carcinoma of the breast: Multicentric study of Turkish Society for Radiation Oncology breast cancer study group (TROD 06-014 study)

BACKGROUND

Encapsulated papillary carcinoma (EPC) is a rare malignant papillary breast cancer accounting for approximately .5%-2% of all breast tumors. The aim of this multicenter study was to evaluate clinicopathologic features of EPC in addition to oncological outcomes and radiotherapy (RT) details.

METHODS

From 10 different academic hospitals in Turkey, we obtained pathology reports of 80 patients with histologically confirmed EPC between 2005 and 2022. Demographic, diagnostic, and treatment data were collected from medical records, retrospectively. Local failure, distant progression, toxicity-adverse effects, overall survival (OS), and disease-free survival were evaluated, and survival analyzes were performed using the Kaplan-Meier method.

RESULTS

Eighty patients with the diagnosis of misspelled sorry (ECP) were retrospectively evaluated. The median age of the patients was 63 (range, 35-85). After a median follow-up of 48 (range; 6-206) months, local recurrence was observed in three patients (4%). Local recurrence was less common in the patients who received whole breast RT with a tumour bed boost (p = .025). There were not any distant metastasis or disease-related death. RT was applied to 61% of the cases, and no treatment-related grade 3 or higher toxicity was reported in any of the patients. Five year OS, cancer-specific survival (CSS), and  were observed as 85%, 100%, and 96%, respectively.

CONCLUSIONS

ECP is a rare, slow-progressing breast carcinoma associated with good prognosis, it is a disease of elderly patient, and usually occurs in postmenopausal women. It responds extremely well to optimal local treatments and appropriate adjuvant treatments on a patient basis, and has excellent OS and CSS ratios.

Encapsulated papillary carcinoma of the breast: A single institution experience

Encapsulated papillary carcinoma (EPC) is a relatively rare form of breast cancer. To date, no evidence-based guidelines for the treatment of EPC have been established. Between January 2015 and December 2021, patients with histologically confirmed EPC of the breast were recorded in a database by The Third Hospital of Nanchang City (Nanchang, China). A total of 46 patients with EPC were retrieved from the database. Age at diagnosis ranged from 41-88 years (median age, 62 years). A total of 21 of these patients had pure EPC, 6 patients had EPC associated with ductal carcinoma in situ and 19 patients had EPC associated with invasive carcinoma. The majority of EPC cases were low nuclear grade, hormone receptor-positive and human epidermal growth factor receptor-2-negative. Additionally, myoepithelial cells were always absent in the papillae of the EPC. All patients underwent lumpectomy or mastectomy with sentinel lymph node biopsy, and almost all of the patients received adjuvant hormonal therapy. Adjuvant chemotherapy was only suggested to 4 patients who were diagnosed with axillary lymph node involvement. Subsequently, the clinicopathological features of non-invasive EPC were compared with invasive EPC. The results indicated that larger tumor sizes and axillary lymph node metastases were more common in invasive tumors. During the follow-up, only 2 patients with invasive EPC experienced recurrence or metastasis. In conclusion, a substantial proportion of invasive EPC cases display aggressive characteristics and metastatic potential, despite it being considered a subtype of carcinoma in situ with excellent prognosis, and local surgical resection is the initial method of treatment. Therefore, adjuvant endocrine therapy, radiotherapy and chemotherapy should be considered in select patients, especially in those diagnosed with invasive EPC tumors.