Destruction of deeper tissues, and deformity and loss of function in the affected limbs may occur in later stages. It tends to occur in one foot. Mycetoma due to bacteria has similar clinical features. Causes
Eumycetoma is a type of mycetoma caused by fungi. Mycetoma caused by bacteria from the phylum Actinomycetes is different. Both have similar clinical features.The most common fungi causing white discharge is Pseudallescheria boydii. Other causative agents of non-black grain eumycetoma include Acremonium and Fusarium species.Black discharge tends to be caused by species from the genera Madurella, Pyrenochaeta, Exophiala, Leptosphaeria and Curvularia. The most common species are Madurella mycetomatis and Trematospheria grisea (previously called Madurella grisea). Mechanism
The disease is acquired by entry of the fungal spores from the soil through a breach in the skin produced by minor trauma like a thorn prick. The disease then spreads to deeper tissues and also forms sinus tracts leading to skin surface. Mature lesions are characterised by a grainy discharge from these sinuses. These discharges contain fungal colonies and are infective. Spread of infection internally through blood or lymph is uncommon.Infections that produce a black discharge mainly spread subcutaneously. In the red and yellow varieties deep spread occurs early, infiltrating muscles and bones but sparing nerves and tendons, which are highly resistant to the invasion.Botryomycosis, also known as bacterial pseudomycosis, produces a similar clinical picture and is caused usually by Staphylococcus aureus. Other bacteria may also cause botryomycosis.
Diagnosis
Diagnosis is by biopsy, visualising the fungi under the microscope and culture, which show characteristic fungal filaments and vesicles characteristic of the fungi. Other tests include ELISA, immunodiffusion, and PCR with DNA sequencing (so-called DNA barcoding).X rays and ultrasonography may be carried out to assess the extent of the disease. X rays findings are extremely variable. The disease is most often observed at an advanced stage that exhibits extensive destruction of all bones of the foot. Rarely, a single lesion may be seen in the tibia where the picture is identical with chronic osteomyelitis. Cytology of fine needle aspirate or pus from the lesion, and tissue biopsy may be undertaken sometimes. Some publications have claimed a "dot in a circle sign" as a characteristic MRI feature for this condition (this feature has also been described on ultrasound). Differential diagnosis
The following clinical conditions may be considered before diagnosing a patient with mycetoma:

Tuberculous ulcer
Kaposis sarcoma, a vascular tumour of skin usually seen in AIDS. Leprosy
Syphilis
Malignant neoplasm
Tropical ulcer
Botryomycosis, a skin infection usually caused by the bacteria Staphylococcus aureus. Prevention
No vaccine is available. Simple hygienic precautions like wearing shoes or sandals while working in fields, and washing hands and feet at regular intervals may help prevent the disease. Treatment
Surgery combined with itraconazole may be given for up to year when the grains are black. Posaconazole is another option. Voriconazole can be used for infections caused by Fusarium species.Ketoconazole has been used to treat eumycetoma but has many side effects.