Mycetoma, also referred to as Madura foot, eumycetoma, actinomycetoma, or exogenous actinomycosis, is a chronic, slowly progressive infection of the skin and subcutaneous tissue that develops after trauma and subsequent contamination with soil and/or vegetation. The causative organisms come from a variety of different genera of soil-dwelling bacteria and fungi. Causative organisms vary by region, with eumycetoma more common in Africa and India and actinomycetoma more common in Latin America.

Mycetoma is diagnosed most commonly in tropical, subtropical, and equatorial regions of the developing world. They are very rare in children. Risk factors include trauma (thorn puncture, mild abrasion), skin exposure to soil and/or vegetation (often due to farming, carrying crops, walking barefoot), male sex (likely due to increased occupational exposures and possibly hormonal differences), and immunodeficiency.

Mycetomas occur most commonly on the feet and lower extremities, where trauma and subsequent soil exposure are most likely. The rate of growth follows two patterns in children. The first pattern is the typical pattern in adults as well. After initial exposure to the pathologic organism, there is an incubation period of weeks to months before a papule or nodule develops. This slowly expands to form a tumor-like mass that develops subcutaneous abscesses. After about 6-12 months, fistulae appear, which exude purulent material and colored granules several millimeters in diameter. Granules represent large collections of bacteria or fungi, and their color varies depending on the organism present. The second pattern is much milder, with very slow growth of organisms even in long-standing disease. This leads to a more limited appearance, with one or a few sinuses and minimal surrounding tissue involvement. This form may be misdiagnosed as a pyogenic abscess or osteomyelitis.

Mycetoma is typically painless (pain implies secondary bacterial infection or osteomyelitis). Most infections remain localized and may cause significant local destruction. However, systemic spread may occur in immunocompromised children, with development of mycetomas in internal organs.

Related topic: Endogenous actinomycosis