Mucoepidermoid carcinoma of the breast: A case report and literature review focused on radiological findings

Mucoepidermoid carcinoma-a rare salivary gland-type tumor of the breast: are we dealing with primary or secondary?-a case report and literature review

Background

Salivary gland-like tumors are extremely unusual in the breast, and their histology is very similar to primary salivary gland neoplasms. Mucoepidermoid carcinoma (MEC), a common salivary gland tumor, displays an infrequent occurrence in the breast, accounting for a mere 0.2-0.3% incidence. Given its rarity, it is critical to accurately distinguish it from metastatic cases before diagnosing it as a primary breast MEC for appropriate treatment. Currently, there is no consensus on the treatment of MEC, and there is a paucity of literature highlighting the ideal treatment modality, especially for estrogen receptor (ER)-positive cancers. Therefore, the aim of our case report was to underscore the diagnostic process, surgical and adjunctive treatments for our patient with ER-positive, progesterone receptor (PR)-negative and human epidermal growth factor receptor 2 (HER2)-negative MEC while also conducting a literature review to contribute to the limited existing data.

Case Description

A 67-year-old African American woman presented with a lobulated 3.1-cm left breast mass on mammography, for which she underwent ultrasound-guided core needle biopsy that revealed invasive carcinoma with squamous differentiation. The carcinoma was ER-positive, PR-negative and HER2-negative. Subsequently, she underwent a lumpectomy with sentinel lymph node biopsy. Her final pathology revealed an intermediate-grade MEC with negative lymph nodes. She had a past medical history of benign salivary gland tumor, as well as a family history of BReast CAncer gene 1 (BRCA1)-associated breast cancer in her daughter.

Conclusions

MEC of the breast is a rare tumor with a relatively favorable overall prognosis. The early and precise diagnosis of this condition plays a pivotal role in formulating effective treatment strategies and ensuring positive survival rates. Nonetheless, future studies are recommended to further explore the role of surgical approaches and adjuvant therapy to improve treatment outcomes.

A high-grade breast mucoepidermoid carcinoma without MAML2 rearrangement: A case report and literature review

INTRODUCTION

Mucoepidermoid carcinoma (MEC) of the breast is an extremely rare primary breast tumor. Between 1979 and June 2022, only 50 cases were reported. The pathological morphology and biological behavior of breast MEC remain poorly understood.

PATIENT CONCERNS

A 47-year-old female was presented with a 10-day-old left breast mass detected by physical examination.

DIAGNOSES

Ultrasonography could not distinguish whether the breast tumor was benign or malignant. After a biopsy of a breast tumor excision specimen, combined with immunohistochemical results, the patient was diagnosed with high-grade mucoepidermoid breast carcinoma.

INTERVENTIONS

The patient underwent a modified radical mastectomy for her left breast.

OUTCOMES

The patient was still free from local recurrence or metastases at 1-year follow-up.

CONCLUSION

A high-grade MEC case without MAML2 rearrangement shows good recovery without complications. The diagnosis was confirmed by histomorphology and immunohistochemical markers. It is sometimes necessary to distinguish it from adenosquamous, adenoid cystic, or mucinous carcinoma. The primary treatment is surgical resection, and the prognosis is closely related to the pathological grade.

Genomics and tumor microenvironment of breast mucoepidermoid carcinoma based on whole-exome and RNA sequencing

Mammary mucoepidermoid carcinoma (MEC) is a rare entity. The molecular characteristics of breast MEC have not been fully investigated due to its rarity. We performed a retrospective study among 1000 patients with breast carcinomas and identified four cases of breast MEC. Clinical and demographic data were collected. Immunohistochemistry panels which were used to diagnose salivary gland MEC and breast carcinomas were also performed. MAML2 rearrangements were detected by FISH and fusion partners were identified by RNA sequencing. Whole-exome sequencing (WES) was used to reveal the genomes of these four breast MEC. Then, the biological functions and features of breast MEC were further compared with those of invasive breast carcinomas and salivary gland MEC.According to Ellis and Auclair's methods, these four breast MEC could be classified as low-grade breast MEC. All the patients were alive, and disease-free survival (PFS) ranged from 20 months to 67 months. Among these four breast MEC, two cases were triple-negative, and the other two cases were found to be ER positive, with one also showing HER2 equivocal by immunohistochemical staining, but no amplification in FISH. FISH analysis confirmed the presence of the MAML2 translocation in three of four tumors, and CRTC1-MAML2 fusion was confirmed in two of them by RNA-sequencing. The average coverage size of WES for the tumor mutation burden estimation was 32 Mb. MUC4, RP1L1 and QRICH2 mutations were identified in at least three tumors, and these mutation also existed in breast invasive carcinoma databases (TCGA, Cell 2015; TCGA, Nature 2012). The results showed that there were many genes in breast MEC overlapping with the breast invasive carcinoma databases mentioned above, range from 5 to 63 genes (median:21 genes). Next, we assessed immune cell infiltration levels in these tumors. In all these tumors, M2 macrophages and plasma cell were in the high infiltration group. Our breast MEC showed different results from the salivary gland MEC, whose plasma cells were in the low infiltration group. Overall, we first analyzed the genomics and tumor microenvironment of breast mucoepidermoid carcinoma and proposed our hypothesis that although MECs arising in the breast resemble their salivary gland counterparts phenotypically, our findings indicate that breast MECs probably resemble invasive breast carcinomas at the genetic level and immune cell infiltration levels. More cases and in deep research need to be done to further understand this rare carcinoma.

Mucoepidermoid carcinoma of the breast, 3 cases report and literature review

RATIONALE

Mucoepidermoid carcinoma (MEC) is one of the most common malignant tumors in salivary glands, with specific histomorphological and molecular characteristics. MEC occurring in breast is more rare.

PATIENT CONCERNS

We reported 3 cases of female breast mass, diagnosed as benign nodules by ultrasound.

DIAGNOSES

The first 2 cases were pathological diagnosed as breast MEC, low grade, and the third case as breast MEC, medium grade.

INTERVENTIONS

After pathological diagnosis, 3 patients have expanded the scope of breast resection and lymph node dissection, with negative margin and no lymph node metastasis.

OUTCOMES

In the follow-up observation, the first case was followed up for 24 months, the second case was followed up for 30 months, and the third case was followed up for 12 months. All patients had a good prognosis without evidence of recurrence and metastasis.

CONCLUSION

Breast MEC is extremely rare and estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2 negative breast cancer with a good prognosis, which is different from other highly malignant triple-negative breast cancers. reviewed its clinicopathologic morphological characteristics, immunohistochemical markers and molecular characteristics, prognosis and clinical treatment through literature, in order to understanding its clinicopathology and providing reference for clinical precise treatment.