Extraskeletal osteosarcoma in an Egyptian fruit bat (Rousettus aegyptiacus)

Extraskeletal osteosarcomas (EOS) are extremely rare mesenchymal tumours arising in various soft tissue locations. They have been documented in humans and companion animal species. Reports of neoplasia in Chiroptera were previously thought to be rare. However, recent publications have reported a variety of neoplastic tumours in Egyptian fruit bats (Rousettus aegyptiacus). This report describes the clinical presentation and histopathological findings associated with the diagnosis of EOS in a 15-year-old Egyptian fruit bat housed within a zoo. To the authors' knowledge, this is the first report of EOS in aRousettus.