Skin lipoma in an Arabian leopard (Panthera paradus nimr)

Background: The Arabian leopard (Panthera paradus nimr) is the largest living felid in the arid Arabian Peninsula and classified on the IUCN red list as critically endangered. Unlike felids, neoplasia prevalence in canids such as benign lipoma and malignant liposarcoma has been long and well documented. Only until recently a plethora of reports emerged demonstrating that neoplasia occurrence in wild exotic felids is prevailed more than expected. Soft tissue tumors arise from fatty cells form either a benign lipoma or a dangerously malignant liposarcoma. Alarming though, such cellular transformation might endanger the life of an already endangered animal. Case: An intact Arabian male leopard living in captivity at the Oman wildlife animal breeding center (N23.70 E58.09 A5.80 m) aged approximately 18 years and weight 31 kg was admitted to the veterinary clinic for semen collection and routine physical examination. The animal was identified with two large adjacent subcutaneous masses on the upper rear left limb, clinically resembling that of a lipomatosis. Only one large tissue mass was surgically excised from the base with no incident of bleeding. Gross examination revealed a soft, smooth, rubbery, homogeneous, lack of internal fluid and whitish color lobule. Morphometry measurement of the mass shows that the weight, diameter, circumference, thickness and surface area were 3.6 gm, 2.6 cm, 10.2 cm, 3 cm and 17.8 cm³ respectively. On visual examination, neither mucin fluid nor mucosal ulcerations were detected. Microscopically, dark discrete spots were observed on the anterior central and periphery of the mass surface outgrowth. Moreover, histopathological diagnoses with haematoxylin and eosin (HE), masson fontana (MF) and elastic verrhof van giesson (EVG) revealed normal nuclear and non-granular cytoplasm resembling that of a fatty cell originating from a fat adipose tissue. Adipocytes had reasonable amounts of cytoplasm and well defined borders. The nuclei were round to oval shape and no cells were found to be multinucleated. No evidence of high nuclear cytoplasmic ratio was observed. Few lymphocytes and plasma cells were present with no visible lymphatic vessels. Taken together, the lesion was diagnosed as a lobulated soft mass resembling that of an adipose tissue, specifically a benign neoplastic lipoma. Discussion: To date not a single report describes maladies in big cats from arid regions. This is the first study to demonstrate the occurrence of neoplasia in a wild felid namely; the Arabian leopard. Additionally, while recent reports have shown neoplasia occurrence in the Panthera subspecies in tropical, polar and temperate zones, this is the first report to manifest the disease in an arid region. The increase in neoplasm frequency in exotic felids is a concerning fact as numerous members of the Panthera family including the Arabian leopard are classified by the IUCN as endangered or critically endangered species. With less than 200 animals in the wild, only 14 founder individuals in captivity and an aged female population the occurrence of lipoma tumors in the Arabian leopard is a worrisome sign. Taken together, the data suggests the rise of uncommon diseases in carnivores and ubiquitously around different climate zones of the world. Thus highlights the importance of routine physical examinations, investing substantially in diagnostic equipment and healthcare endowment in captive exotic felids.