A reticular pigmented rash on the lower leg

A 10-year-old boy presented to the dermatologist for a spider web-like pigmented rash on the lower right leg. On examination it was found that the rash was expanding medially from the lateral aspect of the leg to ventral part of the foot (Figure 1). The left leg was uninvolved. Erythema was not elevated and disappeared on applying pressure to the area. His history revealed that, on advice of his parents, he had been using an electric heater for the past four winter months to keep his legs warm, prior to appearance of the rash. He had no leg pain, abdominal pain, or any history of recurrent fever. There was no history of systemic disease, and physical examination with CBC was within normal limits. A reticular pigmented rash on the lower leg