An interesting case of childhood brucellosis with unusual features.

: Brucellosis is a zoonotic infection, which is still a major public health concern worldwide. Common clinical findings are usually nonspecific involving fever, arthralgia, myalgia, weakness and malaise. Since none of the symptoms of brucellosis is pathognomonic, it may have a similar course with various multisystemic diseases. In terms of focal involvement, sacroiliitis is the most common musculoskeletal manifestation in adult patients, while it is quite rare in pediatric patients. Blood culture is the gold standard in the diagnosis of brucellosis. In the absence of culture facilities, the diagnosis traditionally relies on serologic testing with a variety of agglutination tests such as the Rose Bengal test and the serum agglutination test. However, these agglutination tests are accompanied by frequent false negative results such as seen in prozone phenomenon, which may lead to diagnostic delays. In this article we present a rarely encountered pediatric brucellosis patient who had sacroiliitis-spondylitis, which are rarely reported in children, and exhibited prozone phenomenon in agglutination tests.