Secondary amyloidosis in ankylosing spondylitis. A systematic survey of 137 patients using abdominal fat aspiration

To assess the frequency and clinical significance of amyloid deposits in abdominal fat in patients with ankylosing spondylitis (AS).

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.

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.

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.