Primary Cutaneous Coccidioidomycosis Presenting on the Leg of an Immunocompetent Patient: A Case Report

Coccidioidomycosis is a fungal infection that primarily manifests as an asymptomatic condition caused by inhalation of fungal spores. Less commonly, patients can develop dissemination to extrapulmonary locations such as the skin or primary cutaneous inoculation of the fungus at a site of trauma. These cutaneous complications are primarily found among immunosuppressed individuals. Here, we present a patient with no relevant past medical history that, after living in an area to which Coccidioides is endemic, developed a slowly growing, pruritic plaque on his right thigh with well-demarcated areas of hypopigmentation and lichenification with erythematous borders; after several inconclusive biopsies, fungal spherules characteristic of coccidioidomycosis were found on pathology. Along with morphologic evidence of trauma at the site of the infection, the most likely diagnosis was determined to be primary cutaneous coccidioidomycosis. This case is notable for several reasons. First, the patient had a persistent cutaneous coccidioidomycosis infection, with a rare clinical presentation, despite no history of immunocompromising conditions or medications. Second, the patient experienced disease progression while on an empiric trial of a Janus Kinase (JAK) inhibitor. Taken together, these findings may suggest a clinical distinction between the presentation of cutaneous fungal infections in immunocompetent and immunocompromised patients.