Figure 3b. Eschar from the bite of a Leptotrombidium mite. (a) Photograph shows an epidermal ulcer covered by a black crust surrounded by an erythematous halo. (b) High-power photomicrograph (original magnification, x400; hematoxylin-eosin stain) shows dermal vasculitis with perivascular infiltrates that consist mostly of lymphocytes and macrophages.