ACR Codes: 33.218
This patient had a pressure ulcer that became super-infected, either through the ulcer itself or from septicemia that developed after the manipulation of the LLE wound. This patient is a good candidate for developing this complication of pressure ulcers given his immunodeficiency (DM) and vascular disease.
Pressure ulcers develop when external compression leads to hypoxia in the epidermis and underlying tissue. These ulcers develop most commonly in the elderly and in bed-ridden patients. Pressure ulcers can be staged and treated accordingly as follows (according to Fitzpatrick's):
Stage I: skin intact; non-blanching erythema. TX: Topical ax w/ moist dressings
Stage II: Ulceration w/ skin breakdown. TX: Topical ax, and wet to dry dressings if needed
Stage III:Full thickness skin breakdown down to fascia. TX: surgical (debride +/- graft)
Stage IV: Full thickness skin breakdown w/ invasion of bone, muscle or other surrounding structures. TX: surgical (debride +/- graft)
According to Rosenburg, 25% of all abscesses occur in the buttocks region. Of the buttocks abscesses, 1/3 are pure aerobes, 1/3 pure anaerobes and 1/3 mixed. Ultra sound of a suspected abscess can help to delineate the abscess margins (especially extension into the muscles) and can show foreign bodies, if present.
Gas in the soft tissue is often due to infection, but other causes should be ruled out. These other causes include surgical introduction or herniation of bowel. The gas in the soft tissue in this patient was indeed proven to be an abscess. Another infectious possibility is the development of gas gangrene, which would present with a "pectinate" appearance of gas infiltrating individual muscle fibers.