Histoplasmosis. Light micrograph of a section through a nodule containing the fungus Histoplasma duboisii, the cause of African histoplasmosis. The spherical yeast cells have thick cell walls. This fungus can invade the skin, liver, lungs, lymphatic system and bony tissues. It creates nodular lesions in cutaneous and bony tissues. Isolated lesions may heal spontaneously or may require surgical removal. Anti-fungal drugs may be used. If histoplasmosis has spread to the liver, prognosis is poor. H. duboisii is closely related to H. capsulatum, the cause of histoplasmosis in North America. Magnification: x70 when printed 10cm wide.