Mycetoma is a localized, chronic, granulomatous infection of subcutaneous tissue with possible extension to underlying bone. Two classifications include eumycetoma, caused by filamentous fungi, and actinomycetoma, caused by bacteria of actinomycetes species. The organism is inoculated into subcutaneous tissue following minor trauma, most commonly the lower extremity and hand, although it may arise anywhere on the body. Both types are similar clinically; eumycetoma, however, causes more morbidity. Initially, a painless subcutaneous swelling is seen with induration, numerous suppurative nodules, and chronically draining sinus tracts. Remote abscesses may rarely be seen due to hematogenous extension. Actinomycetoma occurs more frequently (60%) and has a much better outcome. Mycetomas are rarely fatal but may cause significant dysfunction and disfigurement.
Mycetoma. A eumycetoma with typical chronic sinus drainages in the foot and ankle of a 33-year-old agricultural worker in Peru. Treatment was with itraconazole. (Photo contributors: Rob Griedanus, MD, and Universidad Peruana Cayetano Heredia, Lima, Peru.)
Expulsion of “grains” containing aggregates of the organisms is common. The presence of black grains is diagnostic of a fungal origin, while pale grains could be either fungal or from an actinomycetes species. Further identification of the causative organism may be done by means of various stains, culture, or serology.
Management and Disposition
There is no specific emergency management except recognition and referral. Surgical resection of large lesions may reduce organism load, but relapse rates can be as high as 50%. Amputation is common. Eumycetoma is treated with 1 to 2 years of antifungal agents, while actinomycetoma responds to various combinations of trimethoprim-sulfamethoxazole, dapsone, streptomycin, and amikacin.
Mycetoma is usually seen in young male adults living in rural areas of Africa, Mexico, South America, or India who work as farmers or laborers. Walking or working barefoot is a risk factor for lower extremity disease.
Patients may complain of a deep itching sensation rather than pain. If pain is present, it may indicate secondary infection or bone involvement.
Sweating of the affected area is commonly seen.
A similar condition, botryomycosis, is caused by a chronic Staphylococcus infection with sinus formation.
Mycetoma was first described in the Madura district of India and is often referred to as “Madura foot.”
Mycetoma. A large actinomycetoma of the upper leg with extensive active and healed sinus tracts. (Photo contributors: Stuart Skinner, MD, and Universidad Peruana Cayetano Heredia, Lima, Peru.)
Mycetoma Granules. Sinuses discharge characteristic dark granules (sclerotia) from a eumycetoma. The granules represent microcolonies of the organism. (Photo contributors: Seth W. Wright, MD, and Universidad Peruana Cayetano Heredia, Lima, Peru.)