Introduction: In temperate places pyomyositis is very uncommon in children and adolescents. West European and North American Literature about is relatively poor (104 articles from 1998 to nowadays and most of these papers are case-rep orts). S. Aureus is the etiologic agent in 90% of cases. Muscle of the thighs and hips are the most frequent localisation and severe complications are observed in 10% of cases.

Material and Methods: We reviewed all patients affected by primary pyomyositis and admitted in our Department from 1995 to nowadays. Age, sex, history and clinical findings, general and local risk factors were reported. X-rays, Ultrasonography, MRI, Scintigraphy, Haematological investigation and culture were considered in order to state the imaging and laboratory findings of the disease.

Result: Pyomyositis was diagnosed in three males, aged 11, 13 and 16. There was no evidence of medical or familiar risk factors. Soleus, Otturatorius and Psoas muscles were respectively involved. In all cases fever, local signs of inflammation and pain, neutrophylic leukocytosis, increased ESR and CRP levels were present. Blood culture was positive in one case. Standard X-Rays were normal in all cases. Ultrasound scan, RMI and Scintigraphy were positive but non-specific in all cases. 2 cases underwent to surgical drainage and a 3 weeks antibiotic therapy; 1 case resolved performing only medical treatment (5 weeks of antibiotic). All patients showed complete clinical, haematological, and RMI recovered without reliquates.

Conclusions: Pyomyositis is uncommon in temperate climate and it may be easy misdiagnosed at the onset. In our patients the mean time from onset of symptoms to diagnosis was 10 days. History and clinical examination might be evocative, but there are no pathognomonic haematological or radiological findings so that diagnosis is often the result of extensive and wide considerations. Pyomyositis should be suspected in any unclear septic condition of the musculoskeletal apparatus. High index of suspicion, prompt diagnosis, and early treatment can prevent complications and allow the recovery of this potentially life-threatening disease.