Chronic diarrhea is a common encountered problem in the outpatient setting. Differential includes infectious, inflammatory, and malignant etiologies. We present a rare cause of chronic diarrhea, emphasizing need for physician awareness.
A 68-year-old male presented with chronic diarrhea, up to 12 bowel movements/day with nocturnal stools for the past 12 months. He described diffuse abdominal discomfort, dysgeusia, dysphagia, loss of appetite, & unintentional weight loss of 15 pounds over 1 year. Physical exam was benign. Initial labs including CBC, CMP, ESR, TSH, lipase, and infectious stool studies were unremarkable. An upper endoscopy showed mild antral erythema. Colonoscopy revealed multiple polyps less than 1 cm in size which were removed. Random biopsies were taken from the colon. Biopsies from the stomach, duodenum, and colon demonstrated amyloid deposits with apple-green birefringence on Congo red stain. Patient was referred to a tertiary care center for further evaluation, where a bone marrow biopsy revealed plasma cells expressing monotypic lambda cytoplasmic immunoglobuin light chains with CD38 & CD138, and no CD19 or CD45. This profile was consistent with AL (lambda) type amyloid deposition. He was further found to have amyloid deposits in the kidney, autonomic nerves, and heart. He received treatment with CyBordD (cyclophosphamide, bortezomib, dexamethasone) and an autologous stem cell transplantation. He is now in deep remission of AL amyloidosis.
Chronic diarrhea is a common symptom, but can have a rare underlying etiology, such as amyloidosis. Prompt workup with endoscopy & biopsy with Congo red stain are diagnostically essential. Additionally, as different types of amyloidosis require different therapies, the diagnosis must be confirmed by biopsy with immunostaining. Gastrointestinal (GI) amyloidosis is a rare disease, clinically apparent in one percent of patients with AL (primary) amyloidosis. It can present as any of 4 syndromes: GI bleeding, malabsorption, protein-losing gastroenteropathy, or chronic GI dysmotility. The pathogenesis involves amyloid deposition in the muscularis mucosae, submucosa, and muscularis propria, which leads to protrusions & thickening of the intestinal wall. The prognosis of AL amyloidosis patients with GI involvement is worse than those without, as it may involve other organs and present with advanced disease. Therefore, early recognition, diagnosis, and management are crucial.