Eumycetoma infected tissue sample. Light micrograph of section through a tissue sample from a patient with eumycotic mycetoma, or eumycetoma, caused by Pseudallescheria boydii, an ascomycete mould fungus. Eumycetoma is a chronic granulomatous fungal disease of humans, affecting mainly the limbs, and sometimes the abdominal and chest walls or the head. It is characterised by purulent swellings and boils. In later stages destruction of deeper tissues may occur, causing deformity and loss of function.