# Solid epithelioid peritoneal mesothelioma with pulmonary metastasis in feline

## TL;DR

This paper describes a rare case of peritoneal mesothelioma in a young cat that spread to the lungs, highlighting the challenges in diagnosing this aggressive cancer in felines.

## Contribution

The novelty lies in reporting a rare case of metastatic peritoneal mesothelioma in a young cat, emphasizing its diagnostic challenges and clinical uniqueness.

## Key findings

- A 2-year-old cat was diagnosed with solid epithelioid peritoneal mesothelioma with lung metastasis.
- Immunohistochemical markers like cytokeratin AE1/AE3 and calretinin were crucial for confirming the diagnosis.
- The case underscores the poor prognosis and diagnostic difficulty of mesothelioma in felines.

## Abstract

Mesothelioma is a rare malignant neoplasm that affects the mesothelial cells lining the thoracic and abdominal cavities, such as the pleura, peritoneum, and pericardium. It is most prevalent in dogs and cattle, but the causes of this disease in animals are uncertain. In felines, it mainly affects the pleura, with an unfavorable prognosis. This paper explores a rare case of metastatic peritoneal mesothelioma in a 2-year-old female mixed breed cat, emphasizing its uniqueness due to the feline's age. The patient, previously treated at a private clinic, presented moderate abdominal distension as the only clinical sign. Abdominal ultrasound and peritoneal fluid cytology led to the provisional diagnosis of mesothelioma/carcinomatosis. One day after exploratory laparotomy, the animal died and was subsequently sent for necropsy. During macroscopic analysis, nodules were observed in the peritoneum, diaphragm, omentum, stomach serosa, and large intestine, and the diagnosis of solid epithelioid peritoneal mesothelioma with lung metastasis was confirmed after microscopic analysis. The diagnosis of mesothelioma is challenging, and the importance of immunohistochemical panels with specific markers such as cytokeratin AE1/AE3 and calretinin is highlighted. Considering that mesothelioma is a pathology with a poor prognosis, it is essential to include this disease in the list of differential diagnoses within veterinary oncology.