Introduction

An 8-year-old intact, male French bulldog was presented to necropsy at the Pathology Department of University of Veterinary Medicine, Budapest. It was a case of sudden collapse and death the day before presentation. There was no illness in the dog’s anamnesis.

Objectives

The necropsy was done to examine the cause of sudden death.

Methods

During the necropsy, the following gross pathological lesions were seen. In the thoracic cavity we found 320 ml of mucinous red fluid and several gelatinous soft masses in connection with the pleura, pericardium and sternum. The lungs were collapsed due to the surrounding fluid. No other lesions were found in the body. Pieces of the masses were fixed in 8% neutral buffered formalin and routinely processed and embedded in paraffin blocks. Sections of 3–4 μm thickness were obtained from the blocks and stained with haematoxylin and eosin (H.E.), periodic acid Schiff (PAS), and later immunohistochemistry (IHC) was also performed.

Results

With H.E. and PAS stainings we have seen several spindle-shaped cells in a myxoid stroma, surrounded by many small vessels. The cells were loosely arranged in the stroma. IHC staining with anti-Claudin-5, anti-α-SMA, anti-S-100, anti-CD31, anti-Ki-67 and anti-vimentin primary antibodies proved the diagnosis of angiomyxoma.

Conclusions

Angiomyxoma is a rare type of myxoid tumor in humans and animals. Only a few reported cases exist in veterinary medicine, none of them presented in the thoracic cavity. We report the first case of thoracic angiomyxoma as far as our best knowledge.