Condition	Characteristics
Brown recluse spider bite	Painful bite and lesion within 10 minutes; sinking blue macule with surrounding erythema develops later; central necrosis in 40 percent of bites
Cutaneous anthrax	Pruritic papule develops within one week of infection; evolves into 1- to 2-cm vesicle surrounded by nonpitting edema; rupture and necrosis occur; black eschar follows
Ecthyma	Begins with discrete vesicles, followed by erosion, ulceration, and finally an irregularly shaped eschar
Reaction to “black salve”	Immediate symmetric necrosis after application of salve
Basal cell carcinoma	Smooth, pink to red nodule with pearly borders; ulceration and crusting occur with enlargement