Chronic diarrhea as the presenting feature of primary systemic AL amyloidosis: serendipity or delayed diagnosis?

BACKGROUND Chronic diarrhea in adults is a common symptom with a wide range of underlying etiologies. Although various strategies have been proposed for evaluation, there are still cases with undetermined origins even after extensive workup. Amyloidosis with gastrointestinal (GI) involvement is one of the causes that should be considered in adult patients with chronic diarrhea. We report a case of primary systemic amyloid light-chain (AL) amyloidosis, presenting initially as chronic diarrhea and weight loss. CASE PRESENTATION A 43-year-old man with chronic diarrhea and weight loss was referred to our hospital. Prior to his presentation, extensive evaluation including an exploratory laparotomy was carried out and did not yield any valuable findings. An echocardiography performed after repeated episodes of orthostatic hypotension revealed infiltrative cardiomyopathy. Moreover, biopsies of the terminal ileum revealed amyloid deposition confirmed by Congo Red staining. Finally, a diagnosis of systemic AL amyloidosis was made after hematological workup. Anti-plasma cell therapy did ameliorate his GI symptoms. CONCLUSION Although amyloidosis with GI involvement is a rare cause of chronic diarrhea, it should be considered especially in patients with intestinal malabsorption and extra-GI manifestations, such as orthostatic hypotension. The delayed diagnosis in the present case highlights the importance of recognizing clinical "red flags" not seemingly related to one another, and underscores the need to get intestinal biopsies even with normal endoscopic appearance of the mucosa.