Photo Rounds

Tender, red thigh

A 62-year-old man went to see his family physician (FP) because he was concerned about the tender, red, and swollen area on his right thigh that had been bothering him for 3 days. On exam, his temperature was 99.9° F and his thigh had some purulent drainage. The patient’s blood glucose level was 320 mg/dL. He acknowledged that 2 weeks earlier, he’d run out of his oral medications for his type 2 diabetes.

What's your diagnosis?


The FP diagnosed an abscess with some surrounding cellulitis. An abscess is a collection of pus in infected tissue. The abscess represents a walled-off infection in which there is a pocket of purulence. In abscesses of the skin, the offending organism is almost always Staphylococcus aureus. In 2004, methicillin-resistant S aureus (MRSA) was the most common identifiable cause of skin and soft-tissue infections among patients presenting to emergency departments in 11 US cities. S aureus was isolated from 76% of these infections and 59% of the infections were community-acquired MRSA.

A clinical cure is often obtained with incision and drainage alone. It is reasonable to obtain wound cultures in high-risk patients, those with signs of systemic infection, and in patients with a history of high recurrence rates.

While the patient’s abscess was beginning to drain spontaneously, it needed to drain some more. The FP performed an incision and drained more than 10 mL of pus. The large abscess cavity was packed with non-iodinated gauze (there is no benefit to iodinated gauze and iodine can be toxic to open tissues). The patient was placed on trimethoprim-sulfamethoxazole DS (double strength) twice daily to cover the surrounding cellulitis. His diabetes medications were renewed and he was reminded of the importance of taking (and not skipping) these important medicines.

When the patient returned 2 days later, the erythema was gone and the packing was removed. The patient was feeling much better and his blood sugar was down to 150 mg/dL. The FP inserted a small amount of packing and told the patient that he could remove it himself in 2 days while in the shower. The patient’s culture grew out MRSA sensitive to trimethoprim-sulfamethoxazole. Two weeks later the patient was fully healed, with only a small scar from the incision remaining.

Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Usatine R. Abscess. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. Color Atlas of Family Medicine. 2nd ed. New York, NY: McGraw-Hill;2013:698-701.

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