[A boy with cervical focal myositis].

Area of Science:

• Pediatric Pathology
• Musculoskeletal Diseases
• Diagnostic Imaging

Background:

• Focal myositis is a rare idiopathic condition presenting as a pseudotumor, typically in adult extremities.
• Distinguishing focal myositis from other neck masses can be challenging.

Observation:

• An 8-year-old boy presented with cervical swelling and fever, initially suspected as lymphadenitis.
• Despite antibiotic treatment, symptoms persisted, and MRI suggested a malignant process in the sternocleidomastoid muscle.
• Microscopy revealed lymphoplasmocytic infiltration and muscle degeneration, confirming focal myositis.

Findings:

• Focal myositis can manifest as a cervical tumor in pediatric patients.
• Ultrasound findings are often ambiguous, mimicking lymphadenopathy or malignancy.
• The condition showed significant regression without intervention.

Implications:

• Consider focal myositis in pediatric cervical masses unresponsive to antibiotics.
• Advanced imaging and biopsy are crucial for accurate diagnosis.
• This case highlights the potential for spontaneous resolution of focal myositis.