Multifocal pyomyositis. Diagnosis on technetium-99m MDP bone scan.

Area of Science:

• Medical Microbiology
• Musculoskeletal Imaging
• Pediatric Infectious Diseases

Background:

• Pyomyositis is a bacterial skeletal muscle infection without preceding trauma or a primary infection site.
• It is uncommon in temperate regions and diagnosis can be delayed due to fascial confinement of the infection.
• Differentiating pyomyositis from osteomyelitis and septic arthritis is crucial for appropriate management.

Observation:

• An 11-year-old boy presented with multifocal pyomyositis affecting the elbow and thigh.
• The clinical presentation mimicked other conditions, highlighting diagnostic difficulties.
• Lateral blood pool imaging was utilized for diagnostic assessment.

Findings:

• Bone scans proved valuable in excluding underlying osteomyelitis and septic arthritis.
• Imaging suggested intramuscular infection with liquefaction.
• The case demonstrated multifocal pyomyositis without evidence of bone infection.

Implications:

• This case underscores the utility of bone scintigraphy in diagnosing pyomyositis, especially in multifocal presentations.
• Early and accurate diagnosis is essential to prevent complications associated with deep muscle infections.
• Understanding the imaging characteristics aids clinicians in managing this rare condition in children.