TUMORS OF THE OMASUM.
Papilloma. Sarcoma. Actinomycosis.
Tumors of the omasum have been seen only as papilloma, and sarcoma.
The papillomata result from hypertrophy of the normal papillæ, and their general appearance resembles those of the pharynx, gullet and paunch. They sometimes grow to the size of the fist or larger, with a cauliflower appearance, their increase and the formation of pedicles being favored by the active contractions of the muscular coat of the manifolds. They may be red and vascular if recent, are usually white if older, and may become somewhat horny on the surface, but soft and friable within. When they attain a large size they may obstruct the passage to the fourth stomach, tending to impaction of the manifolds and arresting digestion and nutrition.
Sarcoma of the third stomach has been recorded by Paule, Kitt and Schütz as developing in the subserous tissue and forming a layer on the surface of the organ. This bulges out in rounded swellings of irregular sizes, and may show various degenerations—caseous, calcic or necrotic. The structure shows fusiform and rounded cells more or less numerously imbedded in a fibrous stroma.