Pulmonary myxoma in a sheep.

Pulmonary myxomas are rare in domestic animals and only two cases have been reported previously in sheep. An 8 x 6 x 4 cm mass was detected in the diaphragmatic lobe of the right lung of a 4-year-old Persian Karakul ewe. The mass was well demarcated, multilobulated, soft in consistency and white in colour. The cut surface exuded a mucoid substance and a distinct capsule was evident. Microscopically, the tumour comprised a hypocellular myxomatous matrix, rich in acid mucopolysaccharides, with scattered spindle-shaped or stellate cells. These cells had uniform, oval-shaped nuclei without visible nucleoli and expressed vimentin and S100 on immunohistochemical examination. These gross, microscopical and immunohistochemical features are characteristics of myxoma.