# Synchronous Diagnosis of Ductal Carcinoma In Situ and Mucoepidermoid Carcinoma of the Parotid Gland: A Rare Case of Dual Primary Malignancy

## TL;DR

A rare case is presented where a patient had two different cancers, ductal carcinoma in situ and mucoepidermoid carcinoma, diagnosed at the same time.

## Contribution

This paper reports a unique case of dual primary malignancies occurring synchronously in a single patient.

## Key findings

- A 76-year-old woman was diagnosed with both ductal carcinoma in situ and low-grade mucoepidermoid carcinoma.
- The case highlights the rare coexistence of two distinct malignancies in the same patient.
- Possible causes include coincidental tumor development, treatment effects, inherited predisposition, or hormonal influences.

## Abstract

The coexistence of two histologically and anatomically distinct malignancies, ductal carcinoma in situ (DCIS) and mucoepidermoid carcinoma (MEC), in the same patient is a clinically rare phenomenon. MECs of the salivary glands, most often arising in the parotid, can display a range of histological grades and clinical courses. We report the case of a 76-year-old woman with a prior diagnosis of hormone receptor-positive DCIS who developed low-grade MEC of the parotid gland nearly a decade later. Possible etiologic factors discussed include coincidental tumor development, prior treatment effects, inherited predisposition, and hormonal influences. A focused literature-based discussion supports the analysis of this unique case.