Pyomyositis mimicking osteomyelitis detected by SPET/CT.

Pyomyositis is a relatively infrequent, sub-acute primary bacterial muscle infection, which due to its non specific clinical findings is unlikely to be early diagnosed especially in diabetic patients. This diagnostic delay may be fatal. Therefore, early diagnosis and prompt treatment are imperative. We present a poorly-controlled diabetic patient who was referred to our Nuclear Medicine department for a bone scan to evaluate osteomyelitis. Routine three-phase-planar-scintigraphy was falsely positive for osteomyelitis in the left fibula, however, single photon emission tomography (SPET/CT) images clearly showed abnormal uptake in the calf muscles rather than the bone with evidence of low-attenuation lesions in these muscles. SPET/CT and magnetic resonance imaging (MRI) provided essential information to the clinicians to consider other diagnoses rather than osteomyelitis. MRI showed inter and intra-muscular collections consistent with multiple abscesses. Based on medical history, SPET/CT and MRI findings, the diagnosis of pyomyositis was established. The patient underwent successfully multiple incision-drainage procedures with subsequent intravenous antibiotic treatment and was discharged after complete recovery. In conclusion we advocate the use of SPET/CT for the detection of pyomyositis.