# Practical pathological methods for reliable diagnosis of secretory carcinomas of the salivary gland

## TL;DR

This study identifies a practical method using mammaglobin and S-100 to accurately diagnose secretory carcinomas of the salivary gland, reducing reliance on costly genetic tests.

## Contribution

The study introduces a combination of mammaglobin and S-100 immunohistochemistry as a reliable diagnostic tool for secretory carcinomas.

## Key findings

- Re-analysis of 31 cases revealed 21 secretory carcinomas and 10 acinic cell carcinomas.
- Combining mammaglobin and S-100 immunohistochemistry improves diagnostic accuracy for secretory carcinomas.
- Pan-Trk was not universally effective for diagnosing secretory carcinomas.

## Abstract

Secretory carcinomas (SCs) of the salivary gland have recently been recognized as low-grade, malignant tumors. Before this designation, most SCs were diagnosed as variants of acinic cell carcinomas (AciCCs). SCs harbor the t(12;15)(p13;q25) translocation that generates an oncogenic fusion gene, ETS variant transcription factor 6/Neurotrophic tyrosine receptor kinase(ETV6::NTRK3). However, detecting fusion genes in a clinical setting is time-consuming and costly. In this study, we examined 31 cases previously diagnosed as AciCC and SC using pathological analyses with detection of fusion genes using ETV6 break-apart fluorescence in-situ hybridization and reverse transcription-polymerase chain reaction. After re-analysis, we found that these 31 cases actually comprised 21 SCs and 10 AciCCs. We examined the diagnostic utility of immunohistochemistry by comparing results with the fusion gene, Pan-Trk, which despite having recently been reported as effective for diagnosis of SC, was not universally accurate. However, combining mammaglobin and S-100 could be particularly useful in diagnosing SC. This practical method will contribute to accurate diagnosis of SCs, while saving time in daily clinical practice.

The online version contains supplementary material available at 10.1007/s12672-025-03072-3.