Painless foot swelling with a chronic purulent discharge

DIFFERENTIAL DIAGNOSIS The differential diagnosis of mycetoma includes chronic osteomyelitis resulting from bacteria, mycobacteria, or actinomycosis; other deep fungal infections, such as blastomycosis, coccidioidomycosis, or sporotrichosis; botryomycosis; leishmaniasis; yaws; syphilis; and chromoblastomycosis. 2 , 4 The diagnosis is determined on the basis of microscopic examination of pus and granules with potassium hydroxide preparation, Gram stain, and acid-fast stains of smears and by culture of the grains. 4 , 5 The shape and color of the grains, along with their appearance in tissue subjected to skin biopsy, may be helpful in identifying the causative agent. 2 , 4 TREATMENT Treatment of mycetoma is difficult, in part because the condition is usually in an advanced stage by the time the diagnosis is made.