Adenoid cystic carcinoma of the breast with distant metastasis to the liver and spleen: a case report

Locally Advanced Adenoid Cystic Carcinoma of the Breast-A Case Report with a Review of the Literature

Breast cancer (BC) is a heterogeneous disease distinguished by four main subtypes based on the expression of estrogen, progesterone receptors, and human epidermal growth factor-2 on the cancer cells. Triple-negative breast cancer (TNBC) consists of approximately 10-20% of all BCs and is characterized by a poor prognosis. Adenoid cystic carcinoma (ACC) of the breast is a rare, special type of TNBC with low metastatic potential and usually favorable prognosis. There are no established recommendations concerning systemic therapy in advanced ACC. We present a case of a 70-year-old woman with locally advanced ACC with progression after radical mastectomy, and review the literature concerning the treatment of metastatic disease focused on systemic therapy.

Disease Behavior and Treatment Response of Special Histological Types of Triple-Negative Breast Cancer

BACKGROUND

Special histological types (SHT) of triple-negative breast cancer (TNBC) are a heterogeneous group of rare poorly understood diseases. We aimed to evaluate the clinical features, treatment, and outcomes of patients with SHT of TNBC.

METHODS

We evaluated patients with a SHT of TNBC treated in a cancer center between 2009 and 2020. The endpoints were characterization of clinical and pathological features, pathologic complete response (PCR) rate after neoadjuvant chemotherapy, disease-free survival (DFS), progression-free survival, and overall survival (OS).

RESULTS

The 132 patients included had the following histologies: metaplastic (n=71), medullary pattern (n=14), lobular (n=12), adenoid cystic (n=12), apocrine (n=10), and others (n=13). Metaplastic, lobular, and medullary pattern tumors had higher grade (66.6-85.7% grade 3); adenoid cystic and apocrine had mainly grade 1-2 (70-83.3%). Metaplastic and lobular carcinomas had higher disease stages (47.8% and 58.2% stages III-IV). PCR rates were 10.3% for metaplastic and 33.3% for lobular carcinomas, with 5-year DFS rates of 56% and 51.4%. Medullary pattern carcinomas had a great response to treatment, with PCR rate of 100%, and 5-year DFS rate of 92.8%. Apocrine carcinomas also had favorable prognosis, with no recurrence after early disease treatment, and 5-year DFS rate of 83.3%. Adenoid cystic carcinomas had intermediate prognosis, with 5-year DFS rate of 66.6%.

CONCLUSION

SHT of TNBC encompasses heterogeneous malignancies with distinct behaviors. Lobular and metaplastic carcinomas showed high aggressiveness and poor treatment response, while medullary pattern and apocrine carcinomas had favorable outcomes. Treatment strategies focus on molecular features of each of these diseases are warranted.

Adenoid Cystic Carcinoma of the Breast: A Case Report

Adenoid cystic carcinoma (ACC), characterized by proliferating glands and stromal and basement membrane elements, is a tumor most commonly occurring in the salivary glands; very rarely does this tumor present as a primary tumor in the breast. We present the case of a 53-year-old female who presented with a breast mass noted to be concerning on imaging and confirmed to be ACC on biopsy. The mass was amenable to surgical excision with referrals to medical and radiation oncology. Due to the rarity of the disease, there is no consensus regarding the optimal treatment strategy for the pathology, including the use of chemotherapy and radiation. Long-term follow-up is, however, recommended in order to monitor for recurrence.