The fish-tank granuloma affects more commonly the fin-
gers or dorsum of the hand but it has also been described on the foot and other anatomical sites. M. marinum frequently infects freshwater fish and, hence, individuals handling fish tanks represent the main population at risk (Gray et al., 1990). Direct inoculation into the foot presents with similar clinical findings to those found in infections of the upper limb. The disease manifests as a localised, progressing swelling with variable pain, and the appearance, within a few weeks, of nodular or verrucous skin lesions on the affected area. These lesions can show ulceration and bleeding from the disease process itself but also from mechanical trauma. The nodular lesions, measuring a few millimetres up to 2-3 cm, may resolve spontaneously after a few months, but they can also disseminate proximally by haematogenous or lymphatic spread (Figure 9.14). The dorsal aspects of the hand, foot, and the malleolar regions are exposed to trauma and therefore direct inoculation commonly takes place on these regions. Once the condition is suspected, microbiological and histopathological investigations are the most sensitive tests to confirm the clinical diagnosis.
Leprosy is a chronic disease that affects not only the skin but particularly the peripheral nerves bilaterally. The hands and feet are the anatomical sites where inflammation, characteristic skin lesions, and nerve damage occur in the course of leprosy. The commonest skin lesions are nodules, erythematous plaques, or hypopigmented patches. Symptoms like hypo- or dysaesthesia, together with motor/sensory nerve abnormalities and obvious thickening of peripheral nerve branches, suggest the characteristic demyelinating neuropathy of leprosy. Advanced disease manifests with skin atrophy, pigmentary changes, and in severe cases chronic ulceration leading to mutilation and disability (Figure 9.15). Mutilating lesions of the hands and feet result from bone resorption, mechanical trauma, and secondary bacterial infection.
The clinical diagnosis of leprosy can be easily established in most cases that occur in endemic regions of the world (Bryceson and Pfaltzgraff, 1990). Epidemiological, clinical, histopathological, bacteriological, and immu-nological criteria have been used for many years to
diagnose and classify the cases of leprosy within a disease spectrum. This spectrum considers two polar groups or forms, called tuberculoid and lepromatous, as well as intermediate forms of the disease defined as borderline. Early disease may not present characteristics of any of the above groups and such cases are called indeterminate. The evolution of leprosy is a dynamic process and a significant number of cases cannot be classified easily at the time of diagnosis. All patients require long-term follow-up as their place within the spectrum involves not only therapeutic, but most importantly, prognostic implications. Patients with early disease, and particularly those presenting to the travel specialist in countries nonendemic for leprosy, often pose diagnostic difficulties. The delay in establishing an accurate diagnosis and treatment inevitably results in irreversible nerve damage and chronic complications with variable degrees of disability.
Skin tuberculosis affects individuals of all ages and both sexes, presenting with a wide variety of clinical pictures that frequently affect the lower limbs and particularly one or both feet (Chopra and Vega-Lopez, 1999); however, lupus vulgaris and papulonecrotic tuberculide are more common in females, whereas tuberculosis verrucosa cutis is rare in children. By far the main clinical presentation of cutaneous tuberculosis affecting the adult foot is called tuberculosis verrucosa cutis, whereas cases of lupus vul-garis are commonly observed on the face. The tuberculous bacilli cause disease following direct inoculation into the skin but clinical disease can also result from haema-togenous dissemination. Unilateral and asymmetrical involvement is the rule in almost all cases of skin tuberculosis. Commonly observed asymptomatic lesions include dry patches of atrophic skin, pigmentary changes, nodules, and plaques of verrucous lesions. The typical plaque of tuberculosis can measure between 2 and 12 cm in diameter, but chronic and larger lesions can involve most of the foot dorsum and lateral aspects. The course of cutaneous tuberculosis is indolent and chronic, but determines skin atrophy and variable degrees of scarring with a consequent degree of local skin insufficiency. The clinical diagnosis can be confirmed by histopathology, bacteriology, and PCR investigations.
Buruli ulcer affects mainly young individuals in rural Africa, and particularly in West Africa, where an increase in incidence has been reported (Thangaraj et al., 1999). More than two-thirds of the total of cases present in children below age 15. The initial lesions present as papules or small nodules that slowly increase in size to the point of causing an area of inflammation and subsequently ulceration of the skin. The ulcer characteristically presents with undermined edges and manifests active indolent phagedenism, often involving large areas of the affected limb. A single ulcer or smaller, coalescing ulcers present more frequently on the lower leg above the ankles but other regions of the foot can be involved as well. Oedematous forms may progress rapidly and cause a panniculitis, with destruction of underlying tissues such as fascia and bone. In cases where a large ulceration is followed by healing, contractures of the affected limb result from scarring. Severe scarring and contractures have been identified as a high morbidity factor for disability and up to 10% of these cases require amputation of the deformed limb (Josse et al., 1994).
Management and Treatment of Mycobacterial Infections
All mycobacterial diseases require highly specialised diagnostic investigations that in many cases can only be carried out in a tertiary hospital setting. Most mycobacterial diseases affecting the skin represent public health priorities, not only for the endemic countries where they occur but also at an international level, as established by the World Health Organization (WHO). Following the diagnosis of individual cases, a long-term multidrug therapeutic regimen can be prescribed only by specialised physicians. Mycobacteria are known to develop resistance to antibiotics and it is imperative that all cases are treated with combinations of at least two drugs. The main drugs with antimycobacterial activity are rifampicin, ethambutol, pyrazinamide, clofazimine, sulfone, isoniazid, macrolide antibiotics, tetracyclines, and quinolones. The management of all mycobacterial diseases must include not only the medical treatment but also a full range of educational initiatives aimed at the patient, the community, and health personnel. Early lesions of fish-tank granuloma, skin tuberculosis, and particularly those caused by Buruli ulcer require surgical
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