Primary Mycetoma Osteomyelitis of the Calcaneus With Active Subcutaneous Nodules

Mycetoma is a chronic, local, granulomatous, subcutaneous, slowly progressive inflammatory disease caused by true fungi (eumycetoma) or filamentous bacteria (actinomycetoma), with the classic presentation involving tumefaction, multiple draining sinuses, and grain-filled pus. Both forms of mycetoma present as a progressive, subcutaneous swelling, although actinomycetoma has a more rapid course. Although not unheard of, mycetoma is an unusual cause of pedal osteomyelitis. We present a case report, complete with magnetic resonance images, of subcutaneous nodular calcaneal mycetoma osteomyelitis, which failed initial identification by means of limited bone core biopsy and was then treated with aggressive surgical excision combined with medical treatment.