Systemic amyloidosis often involves the gastrointestinal tract and usually presents as ulceration or polypoid lesions. However, annular stricture of the colon due to amyloidosis is very rare. Amyloidosis develops in appr. 10% of multiple myeloma patients with lambda light chain production, it is usually type AL and not a presenting symptom. Case report: A 73-year-old female patient appeared at our hospital with anaemia, abdominal pain and haematochesia. Colonoscopy revealed a circular narrowing of the sigmoid colon suggesting malignancy. The patient underwent sigmoid resection and rectosigmoideal anastomosis was prepared to relieve mechanical obstruction. Surprisingly the histological finding from the resected specimen was amyloidosis. Subcutaneous fat tissue biopsy established the diagnosis of systemic AA amyloidosis. Immunoelectrophoresis revealed an elevated gamma-globulin fraction with IgG lambda monoclonal component, as well as a different lambda light chain. Therefore bone marrow biopsy was carried out which confirmed the diagnosis of multiple myeloma. Discussion: Our case is a rare example of the extraordinary tumor-mimicking colon amyloidosis that led to the diagnosis of multiple myeloma. Beside haematological treatment, strict follow-up of the colon process and reconsideration of surgical therapy or endoscopic stenting is of great importance.
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