Although pyloric and duodenal
adenomas occasionally occur in cats, limited information is currently available on their phenotypes and molecular features. The present study investigated the pathological features of these
tumors and the mechanisms underlying their
tumorigenesis. Biopsy samples from 8 cats diagnosed with pyloric or duodenal
adenomas were examined by histopathology and immunohistochemistry. Normal pyloric and duodenal tissues of cats were assessed for comparison. All cases showed a papillary growth of cuboidal to columnar cells with eosinophilic, ground-glass cytoplasm.
Mucin in
tumor cells was positive for
periodic acid-Schiff and paradoxical
concanavalin-A staining, but was negative for
Alcian blue. Immunohistochemically,
tumor cells were positive for
cytokeratin (CK) 19 in 8/8 cases and for CK20 in 5/8 cases, and weakly positive for CD10 in 4/8 cases, CK7 in 3/8 cases, and β-
catenin in 2/8 cases. Nuclear accumulation of p53 was not detected in any case.
DNA sequencing analysis identified no KRAS or GNAS mutations in the 4/8 cases and 5/8 cases for which the KRAS and GNAS genes could be amplified. The histological and immunohistochemical features of
tumor cells were similar to those of mucous neck cells and the pyloric gland of normal feline tissue. The morphology of feline pyloric and duodenal
adenomas was consistent with that of pyloric gland
adenoma in humans; however, its molecular pathogenesis may differ given the lack of KRAS and GNAS mutations in the feline
tumors.