Search

Abstract Background Low‐grade intestinal T‐cell lymphoma (LGITL) is the most common intestinal neoplasm in cats. Differentiating LGITL from lymphoplasmacytic enteritis (LPE) is challenging because clinical signs, laboratory results, diagnostic imaging findings, histology, immunohistochemistry, and clonality features may overlap. Objectives To evaluate possible discriminatory clinical, laboratory and ultrasonographic features to differentiate LGITL from LPE. Animals Twenty‐two cats diagnosed with LGITL and 22 cats with LPE based upon histology, immunohistochemistry, and lymphoid clonality. Methods Prospective, cohort study. Cats presented with clinical signs consistent with LGITL or LPE were enrolled prospectively. All data contributing to the diagnostic evaluation was recorded. Results A 3‐variable model (P

Background: Differentiation of low‐grade intestinal T‐cell lymphoma (LGITL) from lymphoplasmacytic enteritis (LPE) in cats is a diagnostic challenge for pathologists. Objective: Characterize histologic, immunohistochemical, and molecular features of LGITL and LPE. Animals Forty‐four client‐owned cats, 22 diagnosed with LGITL and 22 with LPE. Methods: Prospective, cohort study. Clinical suspicion of LGITL or LPE was based on persistent gastrointestinal signs, unresponsive to empirical treatments. All cats underwent a standardized diagnostic evaluation, including biopsy (preferentially full‐thickness), and were diagnosed with LGITL or LPE after review of clinical, laboratory, sonographic, histologic, immunohistochemical, and clonality results. Results: A monomorphic lymphocytic population (22/22, 100%) and in‐depth mucosal infiltration (15/22, 68%) were hallmarks of LGITL. Epithelial patterns (nests and plaques) were significantly more frequent in LGITL (11/22, 50%) than in LPE (1/22, 5%) cases (P =.001). A CD3+ lymphocytic apical‐to‐basal gradient was observed in 9/22 (41%) of LGITL vs 1/22 (5%) of LPE cases (P =.004). Most LPE cases (17/18, 94%) featured marked fibrosis in the superficial part of the lamina propria. The Ki‐67 20%‐ and 30%‐thresholds discriminated between LGITL and LPE within both the epithelium (specificity >95%) and lamina propria (specificity >95%), respectively. All LGITL cases were CD3+ pSTAT3− and pSTAT5+. T‐cell receptor gamma chain gene rearrangements indicated monoclonality in 86% of LGITL cases. Surprisingly, 70% of LPE cases featured monoclonality (40%) or monoclonality on a polyclonal background (30%). Conclusions and Clinical Importance: We identified new histologic, immunohistochemical, and clonality criteria to distinguish LGITL from LPE. [ABSTRACT FROM AUTHOR]

Background: Low‐grade intestinal T‐cell lymphoma (LGITL) is the most common intestinal neoplasm in cats. Differentiating LGITL from lymphoplasmacytic enteritis (LPE) is challenging because clinical signs, laboratory results, diagnostic imaging findings, histology, immunohistochemistry, and clonality features may overlap. Objectives: To evaluate possible discriminatory clinical, laboratory and ultrasonographic features to differentiate LGITL from LPE. Animals Twenty‐two cats diagnosed with LGITL and 22 cats with LPE based upon histology, immunohistochemistry, and lymphoid clonality. Methods: Prospective, cohort study. Cats presented with clinical signs consistent with LGITL or LPE were enrolled prospectively. All data contributing to the diagnostic evaluation was recorded. Results: A 3‐variable model (P <.001) consisting of male sex (P =.01), duration of clinical signs (P =.01), and polyphagia (P =.03) and a 2‐variable model (P <.001) including a rounded jejunal lymph node (P <.001) and ultrasonographic abdominal effusion (P =.04) were both helpful to differentiate LGITL from LPE. Conclusions and Clinical Importance: Most clinical signs and laboratory results are similar between cats diagnosed with LGITL and LPE. However, male sex, a longer duration of clinical signs and polyphagia might help clinicians distinguish LGITL from LPE. On ultrasonography, a rounded jejunal lymph node, and the presence of (albeit small volume) abdominal effusion tended to be more prevalent in cats with LGITL. However, a definitive diagnosis requires comprehensive histopathologic and phenotypic assessment. [ABSTRACT FROM AUTHOR]