A 25-year-old woman is concerned about lesions on the dorsum of her right foot that first appeared about four months ago. Initially, there was one red lesion; several similarly colored lesions manifested within a few weeks. The original lesion darkened from red to brown before gradually fading to its current appearance. All the lesions are asymptomatic.
The patient denies injury to the foot. She denies any history of skin problems, including any similar lesions elsewhere on her body. She describes her general health as “quite good,” aside from mild seasonal allergies. She is taking no medications of any kind.
EXAMINATION
Three macular patches—each about 2.4 cm and roughly round, with sharp margins—are seen on the dorsum of her right foot. There is no palpable component to any of them, nor increased warmth or tenderness. Two are dark reddish brown, with nonblanchable redness. The middle lesion looks quite different—brownish gray—but it too is totally macular. Elsewhere, her type IV Hispanic skin is free of any notable lesions.
A shave biopsy is taken from one of the active (red) lesions. The pathology results indicate capillaritis.
What is the diagnosis?