Lesions Distribution, Nature and Severity Along the Gastrointestinal Tract in Cats With Low‐Grade Intestinal T‐Cell Lymphoma or Lymphoplasmacytic Enteritis

ABSTRACT Background The distribution and severity of lesions in low‐grade intestinal T‐cell lymphoma (LGITL) and lymphoplasmacytic enteritis (LPE) might vary within the gastrointestinal (GI) tract and coexist. Objectives Evaluate the distribution of the lesions in cats diagnosed with LPE or LGITL and assess the presence of concurrent inflammatory infiltrates and lesion severity in LGITL cases. Animals Fifteen cats diagnosed with LGITL and 12 cats with LPE. Methods Prospective descriptive study including cats diagnosed with LGITL or LPE based on histology and immunohistochemistry between 2019 and 2022. Endoscopic and surgical biopsies of all gastrointestinal segments were performed for histopathologic evaluation. For each LGITL case, concurrent inflammatory infiltrates and the severity of histologic lesions were assessed. Results Jejunum was systematically affected, followed by ileum (LGITL: 93% [14/15]; LPE: 92% [11/12]) and duodenum (LGITL: 87% [13/15]; LPE: 100% [12/12]). Stomach (LGITL: 29% [4/14 cats]; LPE: 33% [4/12]) and colonic (LGITL: 2/3; LPE: 3/4) infiltration were less common. Gastroduodenoscopy correctly diagnosed 87% of LGITL cats, but combined upper and lower GI sampling was diagnostic for all LGITL cases. In LGITL cases, stomach exhibited less severe lesions than duodenum, jejunum, and ileum (p < 0.001, respectively). In 9/15 LGITL cats (60%), concomitant inflammation was found in segments infiltrated with neoplastic lymphocytes. Conclusion and Clinical Relevance LGITL shows a heterogeneous distribution within the digestive tract. Endoscopy sampling of the upper and lower GI tract can be considered a first‐line diagnosis method. Signs of concurrent inflammation were found in LGITL cases, supporting a possible continuum between LGITL and LPE.