Mixed primary mucinous cystadenocarcinoma and invasive ductal carcinoma of the breast: a case report and literature review

Abstract

Background: Mucinous cystadenocarcinoma (MCA) mainly occurs in the ovary, pancreas, and appendix, whereas the breast is a rare primary site of occurrence. Invasive ductal carcinoma (IDC) is the most common breast malignancy. Only 31 cases of the breast MCA have been reported in the English literature, and the coexistence of MCA and IDC in the breast are rare.Case Description: Here, we describe a 61-year-old postmenopausal woman with no family history of breast cancer or other breast-related diseases, who presented with a palpable mass in her left breast lasting for 2 months. On ultrasonography examination, the tumor was a cystic-solid lesion with clear boundary.Magnetic resonance imaging (MRI) showed a mass with low signal intensity on T1 weighted imaging and high signal intensity on T2 weighted imaging. Intraoperative frozen sections revealed metastatic tumor cells in one sentinel lymph node (1/4). She then underwent left modified radical mastectomy with axillary dissection. The post-operative pathological examination showed the tumor consisted mostly of MCA (60%), with a small proportion of intermediate-grade IDC. The MCA had a well-demarcated cystic structure with papillary projections and abundant mucoid material. The epithelium lining cystic spaces was tall columnar, with mucin-producing cells that had basally located nuclei. The degree of cytological atypia varied considerably. Axillary lymph nodes were normal (0/15). The MCA was triple-negative for estrogen receptor (ER), progesterone receptor (PR), and HER2, and positive for CK7 but negative for CK20. Through nextgeneration sequencing, no mutations in the BRCA1 and BRCA2 genes were identified in our case, which was not highlighted in prior cases. After surgery, the patient underwent eight cycles of chemotherapy, and she has been disease-free during the 10-month follow-up. In addition to detailing this instance of mixed MCA and IDC of the breast, we reviewed relevant literature and compare our findings with other patients who had breast MCAs.Conclusions: Our results improved the understanding of mixed MCA and IDC, especially MCA, and provided a basis for its diagnosis and differential diagnosis from other metastatic diseases.

Mucinous Cystadenocarcinoma of the Breast with Bone Metastases: First Case Report and Literature Review

“…The extravasation of mucin into the adjacent interstitial tissue is considered a constant feature of breast MCA [4-6, 10, 12, 13, 15, 22, 25-32]. Additionally, in 15 cases (including ours), tumor cells were observed floating singly or in clusters in the mucin, resembling typical breast mucinous carcinoma [4,6,12,13,15,22,[25][26][27][28][30][31][32]. There were 20 cases of ductal carcinoma in situ (DCIS), with or without mucin production, favoring primary carcinoma over metastasis [4-7, 9, 13, 15, 16, 18, 19, 22, 24, 25, 27-31].…”

“…The age of onset of breast MCA has been reported as 41–96 years (average: 61.6 years), and most cases occur in those aged >60 years [3‒32]. The majority of cases of breast MCA were detected early or were locally advanced.…”

Primary breast mucinous cystadenocarcinoma—histopathological analysis

“…In a microscopic examination, the cysts are lined by tall columnar mucinous cells, which are similar to those of endocervical glands, with abundant extracellular and intracellular mucin. IHC shows consistent results with negative steroid hormone receptors status [estrogen (ER−) and progesterone receptor (PR−)], positive cytokeratin 7 (CK7+), negative cytokeratin 20 (CK20−) while various HER2 status (3,4). CK7/CK20 IHC combination is applicable as both primary ovarian and pancreatic MCA are positive for both cytokeratins whilst primary breast MCA shows no expression of cytokeratin 20 (CK20−).…”

Primary Mucinous Cystadenocarcinoma of the Breast Intermixed with Pleomorphic Invasive Lobular Carcinoma: The First Report of This Rare Association

“…Mucinous cystadenocarcinoma (MCA) is an extremely rare variant of invasive breast carcinoma usually presenting as a large (up to 19 cm) multicystic mass, arising in postmenopausal women (average 58 years old) [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. As a distinct and well-documented entity, it has been introduced in the recent 5th edition of WHO classification of tumors of the breast, 2019 [ 32 ].…”

“…First described by Koenig C. and Tavassoli in 1998, MCA of the breast is typically characterized by microscopic cystic spaces lined with bland-appearing tall columnar cells with abundant intracytoplasmic and extracytoplasmic mucin; stratification, tufting and papillary formations are also a common feature [ 2 ]. The degree of nuclear cytological atypia can vary, with focal loss of mucinous secretion and transformation in eosinophilic/squamoid cells [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. Immunohistochemistry often results in a triple negative immunophenotype; however, the prognosis is generally favorable and nodal metastases are unusual [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ,…”