Edematous erythema, subcutaneous plaques, and severe pain in the lower extremities in an immunocompromised patient.

A 57-YEAR-OLD WOMAN WHO RECEIVED A RENAL TRANSPLANT 10 YEARS AGO is admitted for evaluation of edematous erythema, subcutaneous plaques, and severe lower extremity pain for 1 month. She has had a fever (39.2 C) for 10 days but denies headaches, nausea, and vomiting. Her lesions and fever have not responded to 3 separate courses of intravenous antibiotics (penicillin, ceftriaxone, imipenem). She denies any preceding injury or insect bite. Skin examination reveals diffuse tender edematous erythema and multiple ill-defined, indurated subcutaneous plaques on most of the lower extremities, without abscess or ulceration (FIGURE 1). Neurologic examination results are normal. Her medications include mycophenolate mofetil (1.75 g/d), cyclosporine (120 mg/ d), and prednisone (15 mg/d). White blood cell count is normal, with 90% neutrophils; C-reactive protein level is elevated at 31.3 mg/L (298.1 nmol/L). IgG level is 677 mg/dL. Two repeat blood cultures are negative. Ultrasound and magnetic resonance imaging of lower extremities show no sign of abscess. What Would You Do Next?