Isolated IgG4-related disease of terminal ileum: Report of a rare case and review of literature.

Among the class of immune-mediated diseases, immunoglobulin G4-related diseases (IgG4-RDs) are of particular interest due to their occurrence in a vast number of organ systems with varied presentations. Isolated bowel involvement in IgG4-RD is, however, very rare. A 54-year-old woman presented with acute-onset colicky abdominal pain located in the right lower quadrant for the past 6 months with abdominal distention. Abdominal contrast-enhanced computed tomography (CECT) depicted short-segment symmetrical and circumferential thickening of distal ileal loops and the ileocecal junction with accompanying mesenteric lymphadenopathy, raising the possibilities of ileocecal tuberculosis or Crohn's disease, or malignancy. A right hemicolectomy was performed, and the histological examination revealed it to be an isolated ileal IgG4-RD. After a one-year follow-up, no radiological or clinical recurrence or related symptom was noted. This is the second reported case of isolated ileal IgG4-RD to the best of our knowledge, and IgG4-RD should be kept in mind even when the patient presents with segmental bowel thickening along with common possibilities such as tuberculosis or Crohn's disease in this anatomical region.