Presentation
Difficult to bear weight on left lower extremity. Swelling, erythema, and tender to palpation on physical exam.
Patient Data
Focused evaluation along the left medial calf/area of concern/swelling demonstrates increased echogenicity in the deep calf muscles.
There is diffuse bilateral increased signal intensity, involving the subcutaneous fat of the pelvis/hips down to the ankles consistent with diffuse edema. There is more focal high signal fluid along the lateral and anterior medial forelegs along the deep fascia, left greater than right. There is also subcutaneous high signal intensity extending to the deep fascia, left greater than right, along the lateral and medial of the distal femurs to the knees. There are no hip, knee or ankle effusions.
There is abnormal increased STIR signal within the left posterior compartment, including abnormal signal within the soleus, flexor hallucis longus, flexor digitorum longus and gastrocnemius muscles. There is a focal rim-enhancing fluid collection in the posterior compartment, deep to the superficial posterior compartment.
Case Discussion
This is a case of a subperiosteal abscess leading to an overlying myositis that was first noted an ultrasound ordered to assess for a DVT. MRI raised concern for a periosteal abscess. Interventional radiology (IR) and pediatric orthopedic surgery were consulted. Orthopedic surgery opted for nonsurgical management. IR performed a percutaneous drainage of the purulent fluid collection which was positive for 3+ Gram-positive cocci. The culture and smear grew Group A Beta hemolytic Streptococci (Streptococcus pyogenes). The patient significantly improved after starting antibiotics and was eventually discharged without complication.
Co-author:
Travis Bevington, MD
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