Concurrent Phenylketonuria and Pyogenic Sacroiliitis: A Case Report Highlighting Rare Co-Occurrence.

A 19-year-old male patient with phenylketonuria (PKU) was presented to our clinic with complaints of left hip pain and fever for one week. Physical examination and MRI examination showed findings compatible with pyogenic sacroiliitis and an abscess in the left iliopsoas muscle. The patient's clinical and radiological findings improved markedly with empirical antibiotic treatment. Although immune system disorders associated with PKU have been reported previously, to our knowledge, a direct link between PKU and rheumatological diseases has not yet been demonstrated. This case suggests that further research is needed to understand the potential effects of PKU on the immune system and susceptibility to infections.