Background: AL amyloidosis (AL) is a rare plasma cell dyscrasia with an incidence of 8 per million per year. It is the only form of amyloidosis associated with a monoclonal light chain. Most AL patients have involvement of the gastrointestinal (GI) tract, but are asymptomatic. Both malabsorption and steatorrhea are seen in fewer than 5% of these patients. We describe the diagnosis, natural history, and laboratory features of a subgroup of these patients whose presenting symptoms of AL were predominantly GI with laboratory evidence for a malabsorption syndrome. Methods: All patients seen at Mayo Clinic with the diagnoses of amyloidosis and malabsorption between 1/1/60 and 12β1/98 were reviewed. Nineteen patients with small bowel biopsies positive for amyloid and laboratory evidence for a malabsorption syndrome were identified. The presence of AL was documented by a positive M-protein in the serum or urine or presence of a monoclonal plasma cell population by immunohistochemical staining of the bone marrow. Results: The median age of onset was 63 years (range 41-74). The most common presenting symptoms were diarrhea and/or steatorrhea in 94%, anorexia in 42%, and dizziness in 53%. Only 3 of 19 patients received the correct diagnosis upon initial presentation. The most common pre-biopsy diagnosis was inflammatory bowel disease. The most common signs included weight loss in all 19 patients with a median loss of 30 pounds (range 2-134). Orthostatic hypotension was present in 53%. The median time from symptom onset to diagnosis was 7 months. There was evidence for amyloid involvement of other organs in the majority of the patients, including echocardiographic evidence for cardiac involvement in 53% of those tested. Serum creatinine was abnormal (>1.2 mg/dL) in 58% upon presentation and proteinuria was present in 18 of the 19 patients on routine urinalysis. The median 24 hour protein was 1.24 grams. An M-protein in the urine or serum was present in 94%. GI radiographie study results were non-specific and upper endoscopy and colonoscopy were often visually normal or non-specific. Fat aspirate was positive in 89% of those tested. Bone marrow amyloid stains were positive in 36%. Median survival was 11 months from histologie diagnosis. Adverse prognostic indicators by multivariate analysis included weight loss and anemia, with a decreased survival associated with hemoglobin<l 1.0 g/dL (p<0.001 ). Conclusions: AL should be considered in the differential diagnosis of chronic diarrhea or malabsorption. All patients over age 40 should have screening serum and urine immunofixation prior to small bowel biopsy. The presence of proteinuria provides additional evidence for a systemic process.
|Original language||English (US)|
|Issue number||11 PART II|
|State||Published - Jan 1 2000|
ASJC Scopus subject areas
- Cell Biology