Mycetoma: infection with tumefaction, draining sinuses, and "grains".

Mycetoma is a tumorous infection of skin and subcutaneous tissue. It is caused by either actinomycotic bacteria or eumycotic fungi. The three cardinal features are tumefaction or the appearance of indolent inflammatory nodules and secondary fibrosis, formation of sinus tracts and fistulas that may have the ability to penetrate deep tissue, and the presence of grains or granules in the affected tissue and discharge. Although mycetoma is relatively uncommon in the United States, increasing mobility and changes in demographic characteristics should lead to a greater awareness of this disease. Characteristic histopathologic findings and microbiological identification establish the diagnosis. Consequently, when evaluating what might seem like an ordinary skin or fungal infection, we must widen our differential diagnosis to include mycetoma. Effective treatments for actinomycetoma are available, whereas eumycetoma is often difficult to treat.