Malignant pleural mesothelioma in a female Lion (Panthera leo)

Abstract

A B S T R A C TAn 18-year-old female lion (Panthera leo) was referred to the Department of Animal Pathology of the University of Turin (Italy). At necropsy, multiple nodular, 4-20-mm, confluent white firm nodules were scattered throughout the pleural surfaces of the thoracic wall and of the lungs. Histological lesions were represented by proliferations of papillary structures lined by cuboidal basophilic mesothelial cells with large, oval nuclei and abundant granular eosinophilic cytoplasm. Immunohistochemistry revealed immu-noreactivity for pancytokeratin and vimentin. None of the cells expressed calretinin antigen. Asbestos fibers and asbestos bodies were not detected respectively by light microscopy and by Scanning Electron Microscope-Energy Dispersive Spectrometer investigations. On the contrary, chrysotile asbestos were identified in samples from shelter material. Histological and immunohistochemical findings were consistent with the diagnosis of an epithelial malignant mesothelioma. To our best knowledge, this is the first report of a pleural mesothelioma in a lion.

Pathology in Captive Wild Felids at German Zoological Gardens

“…Histologically, they included two biphasic and one epithelioid type. Pleural or pericardial mesotheliomas are rarely described in wild felids including a lion, a clouded leopard and two tigers [10,[53][54][55]. They were graded as malignant tumors with metastasis in one case, and all neoplasms were of the papillary epithelioid type.…”

“…However, no etiology was identified for mesotheliomas in the present study. Similarly, previous observations lacked evidence for intralesional asbestos fibers in affected felids [10,[53][54][55] and therefore other exogenous and endogenous factors have to be considered as potential causes.…”

“…An increased rate of neoplasms may further be indicative of the presence of infectious agents, genetic aberrations or an adverse environment [8,9]. In captive wild felids, a wide range of different neoplasms has been described, most of which are reported as single cases [10][11][12][13][14]. Only a few studies focused on tumor prevalence in larger populations of wild felids and all publically available data originate from zoological gardens in the United States [5,6,15].…”

Fatal hemothorax caused by pleural mesothelioma in a lion

“…Mesothelioma is a cancer that arises from mesothelial cells of the pleura, peritoneum and pericardium, and occasionally from the tunica vaginalis testis (Gibbs & Berry 2008, Bollo et al 2011. This tumor can have a localized to more diffuse distribution and may present as multiple to coalescing nodular, and sessile to more pedunculated structures (Head et al 2002).…”

“…This seems to be the first report of fatal hemothorax caused by pleural mesothelioma in a lion. (Gibbs & Berry 2008, Bollo et al 2011 and it has also been experimentally induced in laboratory rodents, primates and dogs by exposure to asbestos fibers (Bollo et al 2011). Mesothelioma is more frequent in cattle and dogs, but has been occasionally reported in horses, cats, pigs, a mouse and a goat (Krametter et al 2004, Stoica et al 2004, Brown et al 2007.…”