Clinical Reasoning: A 63-year-old-woman presenting with bilateral leg pain.

A 63-year-old Hispanic woman presented with 5 days of abrupt onset bilateral leg pain. The pain was maximal at onset and worst in her hamstrings and calves. She described it as “soreness, like lactic acid buildup after a workout.” Touch or muscle use exacerbated the pain. It was not accompanied by muscle spasm, numbness, or tingling. She reported mild weakness and difficulty walking due to pain. She reported no symptoms above the waist. There were no constitutional symptoms, swollen joints, or bowel or bladder incontinence. She had no known infections in the weeks before symptom onset. There was no recent strenuous exercise or physical activity. She had 2+ pitting edema of both legs at baseline.