44 yom leg discoloration

44 yom presented with right leg swelling and discoloration. Recently diagnosed with HFrEF 20%. Temp 102.8. Ecchymosis in the right foot and ankle with erythema extending up the right lower extremity and right thigh new since overnight. He did not know that he had a fever, and does not complain of any pain.

Placed US linear probe first on normal left leg (clip 1) and then discolored and swollen right leg calf, lateral leg and distal thigh (clips 2 and 3).

Unaffected contralateral leg with mild cobble stoning and normal muscle appearance.

Affected leg: left proximal calf, large area of complex (heterogeneous) fluid collection with violation of fascial plane concerning for necrotizing fasciitis.

Affected leg: easily compressible large fluid collection violating fascia.

US findings of Necrotizing fasciitis STAFF (https://coreem.net/core/ultrasound-diagnosis-of-necrotizing-soft-tissue-infections/):  

• Subcutaneous Thickening

• Air in the subcutaneous tissue may appear as dirty air shadowing

• FF fascial fluid layer greater than or equal to 2 mm

Air in subcutaneous tissue with “dirty shadowing” suggestive of necrotizing fasciitis.

Fascial fluid layer >2mm suggestive of necrotizing fasciitis. Also noted hyperechoic “hot fat” consistent with surrounding inflammation.

Fasciitis, while rare, is life threatening. Delays in diagnosis and treatment lead to significant morbidity and mortality. Ultrasound, most often using a linear probe, can lead to early detection. When an infection involves the fascial planes it can spread and progress quickly. Classically CT and MRI are used to assist with diagnosis but these studies can cause delays.   Definitive management is surgical removal and debridement.  

This patient underwent CT imaging to confirm diagnosis and was ultimately taken for operative debridement.