Smooth muscle neoplasia of suspected oviductal origin in the cloaca of a blue-fronted Amazon parrot (Amazona aestiva)

A blue-fronted Amazon parrot (Amazona aestiva) was examined because of intermittent cloacal prolapse of 1-month duration. A 2-cm erythematous mass was found protruding from the cloaca and was excised. The histologic diagnosis of the mass was leiomyosarcoma. Eight months later, the parrot was examined a second time because of cloacal prolapse. A 1.5-cm mass protruded from the cloaca, and an aggressive radical excision of the mass was done. Results of histologic examination of this mass were consistant with leiomyoma. The suspected tissue of origin was the uterus or oviduct, of which only a remnant was found after removal of the tumor. The disparity in the histologic diagnosis of the two masses was thought to reflect variability in tumor behavior. This unique case of leiomyosarcoma presenting as a cloacal mass in an Amazon parrot confirms the importance of histologic evaluation of all cloacal masses.