Male predominance is a constant finding in mycetoma with a sex ratio of 3:1. This is commonly attributed to the greater risk of exposure to organisms in the soil during the outdoor activities but many reports are questioning this. No age is exempted but mycetoma commonly affects adults between 15-30 years of age and these are the earning members of the society especially in under developed countries. However, in endemic regions children and elderly people may also be affected.
The clinical presentation of mycetoma is almost identical irrespective of the causal organism. However, the rate of progress is more rapid with actinomycetoma than with eumycetoma. In eumycetoma, the lesion grows slowly with clear defined margins and remains encapsulated for a long period, whereas, in actinomycetoma the lesion is not encapsulated, more inflammatory, more destructive and invades the bone at an earlier period.
The characteristic triad, of a painless subcutaneous mass, sinuses and the presence of discharge containing grains are pathognomic of mycetoma. It presents as a slowly progressive painless subcutaneous swelling sometimes at the site of previous trauma. The swelling is usually firm and rounded but it may be soft, lobulated, rarely cystic and it is often mobile.
Multiple secondary nodules then evolve as well, the nodules may suppurate and drain through multiple sinuses tracts and these sinuses may close transiently after discharge during the active phase of the disease. Fresh adjacent sinuses may open while some of the old ones may heal completely. They are connected with each other, with deep abscesses and with the skin surface.
The discharge is usually serous, serosanguinous or purulent. During the active phase of the disease, the sinuses discharge grains, the colour of which depends on the causative organism. The grains can be black, yellow, white or red and they are of variable size and consistency. The black grains are usually due to M. mycetomatis, the red ones are due to A. pelletierii, the yellow are due to Streptomyces somaliensis and the white grains can be due to A. madurae. Pus, exudate, the dressing gauze and biopsy material should be examined for the presence of the grains.
Mycetoma is usually painless in nature, it was suggested that, mycetoma produces substances that have an anaesthetic action. At a late stage of the disease, the pain may become negligible due to nerve damage by the tense fibrous tissue reaction. Pain may be produced by secondary bacterial infection.
As the mycetoma granuloma increases in size, the skin over it becomes attached and stretched. The skin may become smooth, shiny and areas of hypo or hyper-pigmentation may develop.
Local hyperhidrosis in the skin overlying the lesion is commonly seen in mycetoma. This corresponds with the hyperplasia and hypertrophy of sweat glands found in surgical biopsies. This can be explained by the increase in local temperature that is the result of increased blood flow to the area induced by the chronic inflammatory process. The increased local blood flow in mycetoma was confirmed by an angiographic study, which showed dilated and tortuous terminal arterial branches, vascular blush and dilated veins proximal to the lesion.
Mycetoma eventually invades the subcutaneous tissue, fat, muscles and bone. This is usually gradual and delayed in eumycetoma while in actinomycetomait is earlier and extensive especially in infections induced by A. pelletierii.
For unknown reasons, the tendons and the nerves are curiously spared until very late in the disease process, this may explain the rarity of neurological and trophic changes even in patients with long-standing mycetoma. The absence of trophic changes may also be explained by the adequate blood supply in the mycetoma area.
In the majority of patients, the regional lymph nodes are small and shotty. An enlarged regional lymph node is not uncommon and this may be due to secondary bacterial infection, genuine lymphatic spread of mycetoma or it may be due to immune complex deposition as part of a local immune response to mycetoma infection.
The infection remains localised and the constitutional disturbances are rare but when they do occur, they are generally due to secondary bacterial infection of the open sinuses tracts, fistula formation in some patients or generalised immuno-suppression.
Cachexia and anaemia may be seen in late mycetoma. This is often due to malnutrition, sepsis and mental depression. Mycetoma can produce many disabilities, distortion and deformity. It can be fatal especially with cranial mycetoma.
Secondary bacterial infection commonly occurs in mycetoma. In material obtained by deep swabs and fine needle aspiration, 65% of patients have concomitant superficial bacterial infection; of these 56% are attributable to Staphylococcus aureus, 34% to Streptococcus pyogenes and 10% to Proteus mirabilis.
The co-existing bacterial infections disturb the local environment and reduce the responses to various antifungal and antimicrobial agents. Elimination of co-existing infection results in better clinical response.
It is interesting to note that in a recent study from a mycetoma endemic village in the Sudan, the villagers knowledge of the disease was poor in 96.3% of them, 70% had appropriate attitudes and beliefs towards interaction with mycetoma patients and treatment methods, and 49% used satisfactory or good practices in the management of mycetoma. This indicates the need for objective and effective health education to improve awareness among affected communities.