Therapeutics in Dermatology
A reference textbook in dermatology

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6 June 2012, by DEVELOUX M.

Mycetomas are pathological processes in which exogenic fungal or actinomycosic etiologic agents produce parasite grains. This definition excludes true endogenic Actinomyces israeii actinomycosis.

Mycetomas are infections arising in semi-arid tropical regions. The main endemic areas are Mexico, Africa on either side of the 15th parallel north, the Middle East and India. While most cases in Europe are observed in immigrants from endemic regions, a limited number have been reported in indigenous Europeans. Actinomycosis infections are more prevalent than fungal mycetomas [1].

The infectious agents live in saprophytes in the soil and plants (thorny). They enter the body through cuts and scratches, which explains the prevalence of the diseases in rural areas. More men than women are affected and the incidence is higher in the 20 to 40 age group.

The typical forms are easy to diagnose. In more than 70 percent of cases, a single lesion is present on the foot. The clinical appearance is suggestive of a fistular tumour ("Madura foot"). The fistulas weep pus containing grains that are often visible to the naked eye. The main differential diagnoses are Kaposi’s disease, tuberculosis, oesteomyelitis or another severe fungal infection.

The diagnosis is confirmed by the direct examination of the grains and/or pus, cultures and histology. The colour of the grains is very important: black grains are always fungal (Madurella mycetomatis, Leptosphaeria senegalensis), red are always from actinomyces (Actinomadura pelletieri) and white and yellow grains can be either fungal (Pseudallecheria boydi) or actinomycosic (Nocardia sp, Actinomadura madurae).

This disease has a chronic course lasting several years and causing, in the long run, various complications, the most severe of which involve the bone. At this stage, it becomes extremely debilitating.

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