[Monosymptomatic familial Mediterranean fever as the cause of fever of unknown origin].

A previously healthy 2 year old female child developed fever of unknown origin recurring in monthly cycles. The periodic fever attacks, family history and ethnologic criteria were in agreement with familial mediterranean fever, although further more major symptoms were missing. It was highly unusual to find repeatedly raised levels of angiotensin I converting enzyme, a finding previously not described in literature. Excluding any other differential diagnosis by intensive investigations, together with a positive metaraminol provocation test, the diagnosis of a rare, monosymptomatic variant of familial mediterranean fever was proposed. Amyloidosis was excluded by rectal biopsy. Monosymptomatic familial mediterranean fever is very seldom. We suggest to measure routinely angiotensin I converting enzyme for further evaluation of our findings.