Objective: To assess the frequency and clinical significance of amyloid deposits in abdominal fat in patients with ankylosing spondylitis (AS).
Methods: Abdominal subcutaneous fat aspiration (ASFA) by fine needle was performed in 137 unselected patients with AS of more than 5 years of disease evolution. A followup study was done of patients with amyloidosis in the abdominal fat (ASFA positive test) to evaluate the development of clinical amyloidosis.
Results: In 10 (9M/1F) patients with AS, the ASFA revealed amyloid deposits (prevalence of 7%). Patients with AS and an ASFA+ test were older and had more active and severe disease than those without AS. Only 2 ASFA positive test patients had clinical amyloidosis at the time of the test. After a followup period of 2-10 yrs (mean 5.4 +/- 3.2 yrs), 3 more patients developed symptomatology due to amyloidosis. All 5 patients with clinical amyloidosis showed nephropathy, and proteinuria was found in each. The remaining patients did not develop clinical amyloidosis during followup.
Conclusion: Amyloid deposits in abdominal fat are not a rare finding in AS. A significant proportion of these patients do not develop clinical amyloidosis after a followup of several years. Thus, an ASFA + test in patients with AS is not always associated with a poor prognosis at least in the short term, although longer followup is required.