John S. Herndon, MD1, Kirk Russ, MD1, Sameer Al Diffalha, MD2; 1University of Alabama, Birmingham, AL; 2UAB, Birmingham, AL
Introduction: We present a case of a common clinical problem encountered by gastroenterologists (chronic diarrhea) with a rare underlying etiology. This case highlights the importance of avoiding anchoring on negative test results and considering alternative diagnoses when there is a lack of improvement with empiric therapy and/or new signs or symptoms that arise.
Methods: A 70-year-old male with prostate cancer treated with radiation therapy was admitted with postprandial abdominal pain, distention, and intermittent nonbloody diarrhea for several months. Vital signs were normal. On physical exam, abdomen was soft, nontender, and mildly distended. CBC with differential, CMP, and lipase were normal. Stool culture was negative for Giardia and C. difficile. Contrasted CT abdomen & pelvis showed partial small bowel obstruction with multifocal areas of thickened small bowel and colon (Figure 1). With conservative management, partial small bowel obstruction resolved. Colonoscopy with poor bowel prep was notable for radiation proctitis. EGD with gastric and duodenal biopsies was unremarkable. Repeat colonoscopy again showed radiation proctitis and an area of erythematous mucosa in the sigmoid colon (Figure 2) with unremarkable biopsies. Empiric trials of steroids (for possible Crohn’s disease) and two courses of antibiotics (for small intestinal bacterial overgrowth) failed to improve symptoms. Surgical small intestinal biopsy was considered, but due to frustration he was lost to GI follow up. He continued to see his PCP and began to complain of tongue swelling, raising concern for amyloidosis. Tongue biopsy and later bone marrow biopsy were performed. Both were negative for amyloidosis and malignancy. Congo red staining was then performed on previous gastric and colon biopsies with positive result (Figure 3). Mass spectrometry confirmed AL amyloidosis. The patient underwent autologous stem cell transplant and remains disease free for > 2 years follow up. Discussion: GI amyloidosis is uncommon but can present with GI bleeding, malabsorption, protein losing enteropathy, and/or GI dysmotility. If suspicion is high, Congo red staining should be requested. Treatment is autologous hematopoietic cell transplant or chemotherapy. This case illustrates the importance of considering alternative diagnoses when findings remain unexplained, there is lack of improvement with empiric therapy, and/or new signs or symptoms arise. Negative biopsies do not always = normal.
Contrasted CT Abdomen/Pelvis with small bowel thickening (arrows)
Erythematous mucosa in sigmoid colon
Hematoxylin and Eosin stained section shows a submucosal thickening with associated amorphous pink material deposits. B-C show small blood vessels with abnormal wall thickening. D. Congo red special satin under polarized light showing the amyloid depositing in the blood vessels with its characteristic “apple green” birefringence.
Disclosures: John Herndon indicated no relevant financial relationships. Kirk Russ indicated no relevant financial relationships. Sameer Al Diffalha indicated no relevant financial relationships.