# Inflammatory Mammary Carcinoma in a Captive Bengal Tiger (Panthera tigris tigris) with Lymph Node and Pulmonary Metastases

## TL;DR

A Bengal tiger was diagnosed with aggressive inflammatory mammary carcinoma, which spread to lymph nodes and the lung, emphasizing the need for thorough tissue sampling for accurate diagnosis.

## Contribution

This is the first documented case of inflammatory mammary carcinoma in a Bengal tiger, highlighting diagnostic challenges and sampling requirements.

## Key findings

- Inflammatory mammary carcinoma was confirmed in a Bengal tiger with metastases to lymph nodes and the lung.
- Tumor emboli in dermal lymphatic vessels were cytokeratin positive, supporting the IMC diagnosis.
- Full-thickness skin and subcutis sampling is essential for diagnosing IMC due to tumor extension into superficial dermis.

## Abstract

Inflammatory mammary carcinoma (IMC) is a rapidly progressive mammary cancer in which tumor cells spread through superficial skin lymphatic vessels, leading to marked skin inflammation and early metastasis. We describe IMC in a captive Bengal tiger (Panthera tigris tigris) that showed large abdominal mammary masses, regional lymph node enlargement, and a pulmonary nodule on computed tomography. Necropsy and histopathology identified an invasive cribriform mammary carcinoma with severe tumor-associated inflammation and extension toward the superficial dermis. Tumor emboli were present within dermal lymphatic vessels and were confirmed as epithelial by cytokeratin immunostaining. Metastatic carcinoma was detected in regional lymph nodes and the lung, and neoplastic cells coexpressed cytokeratin and vimentin. This case emphasizes that IMC confirmation is sampling dependent and requires intentional submission of full-thickness skin and adjacent subcutis to evaluate dermal lymphatics.

Inflammatory mammary carcinoma (IMC) is an aggressive mammary carcinoma phenotype characterized by tumor emboli within superficial dermal lymphatic vessels and early metastasis. A captive Bengal tiger (Panthera tigris tigris) presented with large abdominal mammary masses and regional lymphadenopathy; contrast-enhanced computed tomography also revealed a pulmonary nodule. Postmortem examination and histopathology confirmed mammary carcinoma with dermal lymphatic tumor emboli and metastases to regional lymph nodes and the lung. Tumor emboli were cytokeratin positive, supporting epithelial origin and an IMC diagnosis, and neoplastic cells were immunopositive for cytokeratin with concurrent vimentin immunoreactivity. This case highlights the clinicopathologic basis of IMC and the diagnostic importance of including full-thickness skin and adjacent subcutis in the sampling plan.