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.