Metastatic Osteolytic Angioleiomyosarcoma Induced by a Foreign Body in a Kangaroo (Macropus giganteus)

Abstract

An adult female Eastern Grey kangaroo (Macropus giganteus) was examined for lameness due to a mass located at the right tibiotarsal joint. Radiographs revealed a metal arrowhead-shaped foreign body within the mass alongside a pathologic fracture. Grossly, at necropsy, there was a multilobulated and haemorrhagic mass with intralesional metal fragments, associated osteolysis of the tibiotarsus and pulmonary metastatic nodules. Histologically the neoplasm was composed of plump elongated and fusiform cells that often formed concentrically around small vessels. The pulmonary nodules were composed of similar neoplastic cells, necrosis and haemorrhage. Neoplastic cells were positive immunohistochemically for vimentin and smooth muscle actin. The histological features, immunohistochemical profiles and behaviour of this tumour support a diagnosis of a primary angioleiomyosarcoma with lung metastasis associated with a metal foreign body.

Case Report: Unable to Jump Like a Kangaroo Due to Myositis Ossificans Circumscripta

“…The most commonly reported etiology for lameness in macropods are orthopedic diseases including lesions of bones, joints, and ligaments such as fractures ( 1 ), metastatic osteolytic angioleiomyosarcoma ( 2 ), or osteophytes and osteoporosis due to osteofluorotic bone changes ( 3 ). Lameness because of myopathy is reported rarely in kangaroos; the most common myopathy is exertional rhabdomyolysis secondary to stress (capture myopathy) causing acute, severe, generalized weakness, and hyperthermia ( 4 , 5 ).…”