The histopathological features of pale grain eumycetoma.

Histological findings in 24 cases of pale grain eumycetoma have been compared. The inflammatory response and morphology of grains caused by different organisms are very similar. However the histological appearances of Neotestudina rosatii infections, although reminiscent of dermatophyte mycetomas, are distinctive. The characteristic features include the presence of cement and the short swollen hyphal segments. Petriellidium boydii grains are more likely to contain numerous vesicles or swollen hyphae and be surrounded by a prominent eosinophilic fringe. In contrast, Fusarium and Acremonium grains usually have a minimal fringe and contain a dense mass of intermeshing hyphae. However the features separating P. boydii and Fusarium/Acremonium grains are not invariable and can only be used as an approximate guide to the correct identity of the organism.