Salivary Gland–Type Carcinomas of the Breast: A Review and Update With Emphasis on Molecular Advances and Differential Diagnosis

Abstract

Context.— Primary breast carcinomas constitute a divergent group of neoplasms. The classification of breast tumors has been evolving. Recent advances in molecular genetic techniques have enhanced our understanding of these diseases. Integration of state-of-the-art knowledge from research and practice has resulted in the recognition of novel entities as primary carcinomas of the breast with therapeutic and prognostic significance. Objective.— To provide an overview of current concepts in the classification and diagnosis of selective salivary-type carcinomas of the breast, focusing on their salient histologic and immunophenotypic characteristics and recent molecular genetic advancements. Data Sources.— Data were obtained from review of pertinent English-language literature and firsthand experience of the authors as practicing breast pathologists. Conclusions.— The cutting-edge knowledge has led us to further understand a growing number of uncommon types of breast carcinoma that demonstrate morphologic and immunophenotypic resemblance to those more frequently encountered in other organ systems, particularly salivary glands. Some of them also harbor identical molecular genetic alterations to those in their salivary gland counterparts. Yet they typically have diverse prognostic outcomes, thus warranting different clinical management. Accurate diagnosis of these tumors necessitates recognition of salient histologic features and judicious assessment of ancillary studies in the pursuit of precision medicine.