CASE
A 56-year-old man presented to the emergency department with a chief complaint of “rash” on both lower extremities (slightly worse on the left than on the right). The rash first appeared after he completed a round of golf on a warm, sunny day in Charleston, South Carolina, about 6 hours prior to presentation. The gradually developing rash was mildly pruritic. According to the patient, the left lower leg might be slightly swollen, but there was no pain. He reported no chest pain, shortness of breath, or exposure to poison ivy or poison oak. He had not taken any medications or applied any creams or lotions recently. None of his golf round was spent in high grass or weeds. He denied oliguria or dark urine.
Medical history was significant for generalized osteoarthritis and a right knee replacement approximately 3 years previously. He had not seen a physician in more than a year. There was no personal or family history of atopy.
Physical examination revealed a well-nourished, well-hydrated, white male in no acute distress. Pulse was 70 beats per minute and regular; respiration rate, 16 breaths per minute; BP, 118/78 mm Hg; temperature, 97.3°F; and SaO2, 100%. Head, eyes, ears, nose, and throat were unremarkable. Heart and lungs sounded normal. Findings from the abdominal examination were normal. Both legs showed significant diffuse nonpalpable petechiae extending from the knee to the ankle (Figure 1). The rash, which seemed slightly worse on the left leg than the right, stopped abruptly on a circumferential line at the sock line. Both legs demonstrated full range of motion without crepitus. No tenderness was present. A well-healed surgical scar was visible on the right knee. The remainder of the physical examination was unremarkable. A urine dipstick showed just a trace amount of protein; the results from a full urinalysis were completely normal.
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