Primary Gastrointestinal Amyloidosis: An Unusual Cause of Acute Intestinal Pseudo-Obstruction

Amyloidosis of the gastrointestinal tract is an uncommon disorder characterized by the extracellular deposition of an abnormal fibrillar protein. It is rarely proven by biopsy. Amyloid deposition interferes with organ structure and its function. We report a case of a 64-year-old male who presented with severe colicky pain, unable to pass feces, and progressive abdominal distension for 2 days. Physical examination revealed marked abdominal distension, visible peristalsis, high-pitched hyperactive bowel sounds, and generalized tenderness. Plain abdominal radiograph showed markedly diffuse disproportional dilatation of the small bowel with different heights of air-fluid levels in the same loop. Abdominal computed tomography showed an evidence of small bowel obstruction, which revealed no gross mass or cause of obstruction, but long segment narrowing of the terminal ileum was seen. Ileocolonoscopy showed diffuse edematous mucosa of the ileum without mechanical obstruction but loss of normal bowel peristalsis. A random biopsy of the ileum was performed for pathological diagnosis, which reported extensive deposits of amorphous material within the muscle layers and in the submucosal vessels that stained strongly with Congo red and displayed the typical apple-green birefringence of amyloid protein when viewed under plane polarized light. Serum electrophoretic tests disclosed a monoclonal band of IgG-kappa monoclonal protein. His clinical symptoms improved after receiving chemotherapy with melphalan and prednisolone. Our case illustrated the rare cause of acute intestinal obstruction which mimicked a surgical condition. Primary intestinal amyloidosis should be in a differential diagnosis in patients without a demonstrated cause of obstruction.