A Case of Epicardial Epidermoid Cyst in a Crested Porcupine

TL;DR

A wild crested porcupine in Italy had a rare heart cyst, the first of its kind reported in a wild animal.

Contribution

This is the first documented case of an epicardial epidermoid cyst in a wild animal species.

Findings

An epicardial epidermoid cyst was found on the heart of a crested porcupine.

The cyst was lined with stratified squamous epithelium and filled with lamellar keratin.

The lesion was ruptured, causing a lymphoplasmacytic infiltration in the epicardium.

Abstract

One male adult crested porcupine was found moribund in the province of Siena (Tuscany, Central Italy), and died soon after being recovered by a wildlife rescue service. At necropsy, a rounded nodule was noted on the surface of the heart. Differential diagnoses included abscess, systemic tuberculosis, parasitic cyst, and neoplasia. Histology was performed on the lesion, revealing a cystic formation in the epicardium. The cyst was lined by stratified squamous epithelium and was filled with lamellar keratin without hair shafts. The lesion was diagnosed as an epicardial epidermoid cyst (EC). EC are most commonly found in the skin, both in human and animal patients, although rarely they can occur in various internal organs. However, cardiac EC has not been reported before in animals. To the best of our knowledge, this is the first report of EC in a wild animal species.

The crested porcupine (Hystrix cristata) is present in central Italy with an estimated population of 1800 individuals. Despite the local abundance, little data are available on the diseases affecting free-ranging individuals. We describe a case of an epidermoid cyst (EC) in a male adult porcupine found in the municipality of Sovicille, province of Siena (Tuscany). At necropsy, a firm rounded nodule was noted on the left ventricle wall. Histological examination revealed a cystic formation lined by stratified squamous epithelium. The cyst was filled with lamellar keratin, while hair shafts were not present. The adjacent epicardium was infiltrated by lymphoplasmacytic cells in reaction to the rupture of the cyst with the spilling of keratinaceous debris. The lesion was diagnosed as a ruptured epicardial epidermoid cyst. EC are most commonly found in the skin, both in human and animal patients, though infrequently, they can occur in any internal organ. Cardiac EC has not been reported in domestic animals, and this is the first report of EC in a wild animal species. Clinical veterinarians should consider the possibility of similar cardiac lesions in captive subjects since the long lifespan of these rodents could allow the growth of the cyst with the compression of the adjacent tissues.

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