Fever and a Solitary Papule on the Foot

Abstract

A woman in her 30s presented to a tertiary care Boston hospital with a 5-day history of fevers, malaise, headaches, and nausea with a concurrent asymptomatic solitary papule on her right foot. At the time, she was living in a house infested with mice but did not recall any rodent or insect bite. Physical examination revealed a round dusky papule 5 mm in diameter with surrounding erythema on the dorsal aspect of the right foot (Figure, A). No other cutaneous lesions or regional lymphadenopathy were identified. All laboratory tests had normal results except for an elevated monocyte count. Two sterile punch biopsy specimens were sent for culture and histopathologic examination, respectively. Routine hematoxylin-eosin–stained sections are shown in Figure, B and C. What is your diagnosis?