Infective myositis

Case contributed by Muhammad Asadullah Munir
Diagnosis almost certain


Erythema and tender swelling of the distal arm following multiple intramuscular injections over past few months

Patient Data

Age: 60 years
Gender: Male

Mottled lucencies seen along distal arm posteriorly reaching upto the elbow on radiograph.


MRI shows extensive myonecrosis of triceps brachii muscle within posterior compartment of left arm showing multiple air pockets likely due to gas forming organism. The entire length of muscle is involved. Superiorly the deltoid muscle is also involved. There is associated significant edema with blurring of adjacent myofascial planes, more in mid distal arm with involvement of overlying skin. Inflammatory changes also seem extending into forearm along lateral and medial aspect, partly imaged.

The entire humerus and included elbow joints are normal. No osteomyelitis is present.
Mild inflammatory changes around neurovascular bundles at medial aspect of arm and axilla. 
No venous or arterial thrombosis is however appreciated.
Subcentimeter left axillary lymph node are non specific.
Included left hemithorax is normal.

Case Discussion

This was a known diabetic patient who was given multiple IM injections in the left arm.

Over a period of time, he developed erythematous swelling and tenderness over his arm.

Radiograph shows lucencies and swelling over distal arm representing subcutaneous) muscular emphysema.

Subsequent MRI confirmed pockets of abscesses in deltoid and tricep muscles. However, there was no osteomyelitis found.


Case courtesy: Dr. Muhammad Saad Ahmed Jillani (FCPS, EDIR, FRCR)

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