Light chain (AL) amyloidosis following gastrointestinal symptoms that involve multiple organs: a case report

Light chain (AL) amyloidosis is a complex and rare disease characterized by low incidence and diverse clinical manifestations. At the time of diagnosis, most patients exhibit involvement of multiple organs or tissues, leading to severe illness and a poor prognosis. Therefore, early diagnosis, active treatment, and a comprehensive assessment of the disease hold paramount importance. The initial presentation of this rare condition often manifests as gastrointestinal symptoms, posing challenges in clinical identification and differential diagnosis. In this case report, we describe a 70-year-old man with AL amyloidosis, initially misdiagnosed as irritable bowel syndrome and colon polyps. Subsequently, he experienced a series of complications including renal function impairment, pulmonary nodule, pleural effusion, mediastinal lymph node enlargement, spleen enlargement, reduction of white blood cells, red blood cells and platelets, and small intestinal obstruction. Despite multiple pulmonary nodule biopsy and lymph node biopsy, as well as concurrent splenectomy and partial resection of the small intestine, a clear diagnosis remained elusive. Before admission, diarrhea was aggravated, accompanied by emaciation and fatigue. Following the completion of serum immunofixed protein electrophoresis, renal biopsy, bone marrow and rectal biopsy, a conclusive diagnosis of AL amyloidosis involving multiple organs (Mayo 2012 revision stage III) was finally confirmed after a 12-year period. Treatment with proteasome inhibitors, immunomodulators, and glucocorticoids was recommended. The patient underwent methylprednisolone treatment and was discharged after symptom improvement. However, eight months into the follow-up, the patient succumbed to multiple organ failure. The repeated misdiagnoses over the past 12 years were attributed to limited perspectives among some specialists who did not conduct a systematic and detailed medical history analysis or comprehensive physical examinations. Additionally, they did not strictly follow the principle of "monism" in diagnosis. On the contrary, early diagnosis and active treatment of the disease are of great significance to improve the prognosis.