Basal plasmacytosis and eosinophilia for distinguishing inflammatory bowel disease from gastrointestinal tuberculosis on mucosal biopsy

AIMS: Accurate distinction of inflammatory bowel disease (IBD) and gastrointestinal tuberculosis (GITB) on mucosal biopsies remains challenging, especially in South-East Asia. Our previous meta-analysis highlighted that mucosal basal plasmacytosis (BP) can help in identifying IBD although evidence is limited. This study was planned to evaluate the utility of mucosal BP and combined presence of BP and mucosal eosinophilia (ME) (BP+ME) in differentiating ulcerative colitis (UC), Crohn's disease (CD) and GITB using endoscopic mucosal biopsies. METHODS: We retrospectively analysed 500 mucosal biopsies from patients diagnosed with UC, CD and GITB based on clinical, radiological, endoscopic findings and treatment response. Inclusion and exclusion criteria were applied, and histological evaluation was performed independently by two experienced pathologists. Presence of BP and BP+ME was systematically compared across patient groups. RESULTS: Of the 500 biopsies reviewed, 412 met inclusion criteria (UC: 194, CD: 68, GITB: 114, IBD-unclassified: 36). BP was significantly more prevalent in both UC and CD than in GITB. BP+ME was significantly more prevalent in mucosal biopsies from IBD than in GITB. Also, in segmental mucosal biopsies from IBD patients, BP was found significantly more in three or more biopsy fragments than in biopsies from GITB. Both BP and BP+ME demonstrated good diagnostic utility in differentiating IBD from GITB and CD from GITB (positive likelihood ratio 3.24 and 4.35, respectively). CONCLUSIONS: Histological identification of mucosal BP and/or BP+ME provides moderate diagnostic utility in distinguishing IBD from GITB. Identification of BP in three or more biopsy fragments further strengthens histological diagnosis of IBD.