History and Physical Exam
A history of trauma or recent surgery to the affected area may be present, but some cases are idiopathic. Sudden pain and swelling which progresses to anesthesia within hours to days is classic. Fever is typical. Most patients appear toxic, but some appear deceptively well.
The site is erythematous, tender, and edematous with numbness or deep pain out of proportion to the external findings. Discoloration and crepitus are often present. Necrotic, purplish patches appear within 2-4 days. If there is an open wound, gloved fingers can easily separate the skin from the subcutaneous tissue; the fascia will appear yellowish-greenish and necrotic.