Cutaneous vascular hamartoma in a lamb

A male Polwarth lamb with a good body score was born with a pendulous, oval, red mass adhering to the skin in the left ventrolateral thoracic area. The nodule was removed when the lamb was five days old and sent for a gross and histopathological evaluation. Macroscopically, the mass was reddish, slightly oval and flat, well delineated, and contained a central ulcerated area. Microscopically, it showed a marked proliferation of well-differentiated endothelial cells with the formation of new blood vessels. An immunohistochemical analysis showed mild cytoplasmic immunostaining for the von Willebrand Factor in the endothelial cells. To the best of our knowledge, this is the first report of a cutaneous vascular hamartoma in a sheep.