Initial ultrasound imaging was reported as subperiosteal hematoma, however, with no history of trauma and significantly raised inflammatory markers, an MRI was requested which was suggestive of osteomyelitis and subperiosteal abscess. The patient was taken to theater and found to have subperiosteal frank pus at the lateral proximal humerus and frank pus within the humerus medullary cavity. Fluid, tissue and bone cultures grew Group A Streptococcus. The GAS was likely hematogenous spread from a recent boil the patient had on her lower leg.