The diagnostic and clinical significance of granulomas in gastrointestinal biopsies from haematopoietic transplant patients

Aims The diagnostic and clinical significance of granulomas in gastrointestinal (GI) biopsies from haematopoietic transplant patients remains disputed, especially following the proposal of cord colitis syndrome (CCS) as a new entity. The aim of the following study was to explore this controversy by identifying such biopsies with granulomas and detailing their clinicopathological associations. Methods and results Twelve patients with granuloma‐containing biopsies were identified from across three scenarios: prospectively during a GI pathologist’s routine practice over a period of 5 years; retrospectively from a cohort of transplant patients with clinically validated GI graft versus host disease (GVHD); and retrospectively from a cohort of patients who had received umbilical cord blood (UCB). Their clinicopathological assessments (which included unique long‐term patient follow‐up) showed that granulomas are only rarely seen across all GI biopsies from haematopoietic transplant patients, and may uncommonly constitute a histological feature of GI GVHD. Granulomas—and especially well‐defined, non‐cryptolytic ones—are more commonly present in GI biopsies from UCB recipients, but do not show any accompanying histological features that are different from those seen in granuloma‐containing biopsies from other patient groups. Furthermore, the three UCB recipients with granuloma‐containing biopsies were clinically diagnosed with GVHD rather than CCS. Finally, polymorphic post‐transplant lymphoproliferative disorder (PTLD) can present histologically as GI granulomatous inflammation that mimics Crohn’s disease. Conclusions Granulomas in GI biopsies of haematopoietic transplant patients may often indicate a treatable aetiology such as GVHD or PTLD. Granulomas are more commonly seen in GI biopsies from UCB recipients, but do not necessarily indicate a diagnosis of CCS.