CRTC1-MAML2 Fusion in Mucoepidermoid Carcinoma of the Breast

Author Department

Pathology

Document Type

Article, Peer-reviewed

Publication Date

10-2018

Abstract

AIMS:

Mucoepidermoid carcinomas (MEC) are the most common malignant neoplasms of salivary glands but are uncommon in other sites. Salivary gland MEC are most frequently associated with CRTC1-MAML2 translocations. Exceedingly rare MEC of the breast demonstrate a basal-like and often triple (estrogen and progesterone receptor, HER2) negative immunophenotype, with a single case previously reported to show MAML2 rearrangement, although the fusion partner was not known. Comprehensive genomic studies of breast MEC are lacking. In this study, we analyzed the immunophenotype and molecular landscape of two breast MEC to elucidate the pathogenesis of these rare tumors.

METHODS AND RESULTS:

Two breast MEC were subjected to capture-based next-generation DNA sequencing of 479 cancer-related genes. The presence of the CRTC1-MAML2 fusion transcript was interrogated by reverse-transcriptase polymerase chain reaction. In addition, the immunoprofiles of breast MEC were compared to salivary gland MEC. Both breast MEC harbored CRTC1-MAML2 fusions. In contrast to most triple-negative breast carcinomas of no special type, the mutational burden of MEC was very low, with one case demonstrating only an inactivating SETD2 mutation, and the other harboring no somatic variants in genes on the panel. No copy number alterations were identified. The immunoprofiles of breast and salivary gland MEC were overlapping but not identical.

CONCLUSIONS:

The findings highlight MEC as a breast cancer subtype more closely related to its salivary gland counterpart than to basal-like/triple-negative breast cancers of no special type. This article is protected by copyright. All rights reserved.

PMID

30380176

Link to Full Text

Share

COinS