# Metastatic mucinous adenocarcinoma from breast mimicking a pyogenic granuloma in the gingiva: a case report

## TL;DR

A rare case of breast cancer spreading to the gums was mistaken for a benign growth, highlighting the need for careful diagnosis.

## Contribution

This case report adds to the limited literature on metastatic mucinous adenocarcinoma in the oral region and emphasizes diagnostic challenges.

## Key findings

- Metastatic mucinous adenocarcinoma from the breast was diagnosed in a 51-year-old woman with gingival swelling.
- The lesion mimicked a benign pyogenic granuloma, emphasizing the importance of histological and immunohistochemical evaluation.
- Such tumors are rare, accounting for about 1% of oral malignant neoplasms with a predilection for the gingiva.

## Abstract

Mucin-producing adenocarcinomas (MAC) are an extremely rare, indistinct group of neoplasm having either a salivary gland origin or with prominent glandular component. The diagnosis is chiefly based on the histological aspect conjoined with immunohistochemical evaluation as clinico-radiographical features are non-specific. It can arise as a primary metastasis to soft tissues, most commonly from either lung, breast, kidney, or colon. This paper reports a 51-year-old woman with buccolingual gingival swelling having a final diagnosis of metastatic mucinous adenocarcinoma from the breast. A tissue biopsy was performed followed by immunohistochemistry that confirmed the diagnosis. They are extremely rare, making the diagnosis challenging as it may mimic a benign neoplasm. It accounts for approximately 1% of all oral malignant neoplasms having gingival propensity. The clinician should therefore take into account every diagnostic aspect while encountering such oral lesions to achieve proper patient welfare.