Gastric Helicobacter species as a cause of feline gastric lymphoma: a viable hypothesis

Abstract

Gastric Helicobacter spp. are associated with chronic inflammation and neoplastic transformation in humans as well as domestic and laboratory species. The present study examined the association of Helicobacter heilmannii (Hhe) infection in pet cats with feline gastric mucosa associated lymphoid tissue (MALT) lymphoma. Tissues were collected via gastric biopsy or at necropsy from 47 pet cats with clinical signs of gastrointestinal disease, including vomiting and inappetance, and classified as gastritis (14/47), lymphoma (31/37), or normal (2/47). Tissues positive for argyrophilic organisms with Warthin-Starry stain (29/47) were assessed by fluorescent in situ hybridization (FISH) for the presence of Hhe strains 1-4 as well as with a fifth probe that detected Helicobacter salomonis, Helicobacter bizzozeronii, or Helicobacter felis. A significant association of positive Warthin-Starry status with Hhe infection was found in cases of sick cats (22/29; p<0.05 by Chi-square; chi(2)=7.034). Interestingly, a significant association between Hhe status and a diagnosis of lymphoblastic or lymphocytic lymphoma was observed as well in a subset of 24 Warthin-Starry positive lymphoma cases: of lymphoblastic lymphoma cases, 13/17 were positive for Hhe (p<0.05; chi(2)=4.854). Hhe strains 2 and 4 were most commonly found (18/29 and 17/29, respectively) among sick cats, although a higher than expected number of cats was also positive for Hhe1, which initial reports have described as rare in cats and common in humans. The association found between a positive Hhe status with the presence of feline gastric lymphoma, especially lymphoblastic lymphoma, argues for the need to conduct prospective studies to better identify the frequency and strain distribution of Hhe infection in both healthy and clinically ill cats, particularly those cats with gastric lymphoma.

Fig. 1

The image on the left depicts a Warthin–Starry positive stain of gastric tissue positive for Helicobacter heilmannii infection. The image on the right is from the same cat and shows a section of gastric mucosa positive for Hhe4 as detected by FISH. Inset: the distinctive, tight spiral of Hhe4 in the gastric pits is clearly visible in red. This cat had been diagnosed with gastritis by veterinary pathologists.

Fig. 2

Lymphomas were of two major morphologic types, lymphoblastic (10×and 40×, upper left and right) and lymphocytic (10×and 40×, lower left and right). 87% of lymphoblastic lymphomas were positive for Hhe organisms, while the percentage positivity for lymphocytic lymphoma was 12%.