First reported case of peroneal tenosynovitis caused by Coccidioides immitis successfully treated with fluconazole

Coccidioidomycosis is an insidious infection caused by Coccidioides spp (C. immitis and C. posadasii). Disseminated disease occasionally involves tendon sheaths and synovium of the joints leading to tenosynovitis. Here, we describe the case of a 72-year-old woman from southern Arizona, who presented with right ankle pain, redness and swelling for 2 months. Her serum IgG was positive for C. immitis on complement fixation, and her MRI of the right ankle joint showed extensive tenosynovitis of the right peroneal tendons, and subtalar joint effusions with associated synovitis. The purpose of this case is to report an extremely rare manifestation of disseminated C. immitis, that is, peroneal tenosynovitis and challenges involved with diagnosis and treatment. We also document that azole therapy is an effective treatment option for peroneal tenosynovitis caused by C. immitis, and we had to double the dose for slow symptom resolution with 4-week trial with usual 400 mg oral dose of fluconazole.