Tinea nigra is a dermatological disease of a fungal nature that affects the surface layers of the skin of the palms and soles, the areas of the trunk, shoulders and forearms are less likely to suffer. Any subjective symptoms (itching, soreness, burning) this condition does not have, almost its only manifestation is the formation of black or brown spots of various sizes on the skin. Diagnosis of lichen black is made by microscopic examination of skin scraping in the affected area and dermatological examination, general clinical tests and determination of the patient’s immune status play an auxiliary role. Treatment is carried out using traditional antifungal agents.
ICD 10
B36.1 Tinea nigra
General information
Tinea nigra (epidermal cladosporiosis, black microsporosis) is a contagious fungal disease characterized by superficial skin lesions in the palms, feet, less often the trunk and upper extremities. This condition is common in regions with hot and humid climates – mainly in the countries of the tropical belt of America, Africa and Southeast Asia.
For the first time, tinea nigra was described back in 1891, but the etiology of this condition, as well as the causative agent, were determined later. Isolated cases of the disease have been described in Europe, the USA, and Russia, but in most cases it was about fungi brought from tropical regions. Usually the disease occurs in children and young men under 15-18 years of age. The development of tinea nigra can be an indirect sign of diabetes mellitus, immunodeficiency and other conditions accompanied by a weakening of the body’s defenses.
Causes
Several varieties of mold fungi can cause the development of tinea nigra – most often these are Cladosporium wemeckii and Stenella arguata, some experts point to the possibility of similar manifestations when infected with other fungi. In humid and warm climates, fungal spores can stay in the environment for a long time, preserving their infectious properties. Therefore, it is possible to get infected with tinea nigra from a sick person (with a handshake), when using shared towels and other items. Mycelium sprouts from the spores of the fungus, which begins to spread inside the epidermis, forming characteristic lesions of black or brown color.
Risk factors
Low level of ventilation of premises and densely populated dwellings contribute to the long-term preservation of fungal spores and, thereby, increase the risk of infection. Significantly increases the likelihood of getting tinea nigra if you do not follow the rules of personal hygiene.On the part of the macroorganism , infection is favored:
- Violation of the integrity of the skin. The contamination of the dermis occurs when the spores of the pathogen settle on its surface, the risk of developing tinea nigra increases in the case of micro-injuries on the palms or feet, maceration of the skin.
- Low level of human immunity. It may be a consequence of diabetes mellitus, oncological pathologies, taking antibiotics and other potent drugs. In many cases, lichen black develops against the background of complicated acclimatization of a person to a new warm and humid climate for him.
Symptoms
Incubation period
After the spores get on the skin (infection), the manifestations of tinea nigra do not occur immediately, but after the incubation period. Its duration depends on many factors – the reactivity of the body, the activity of the immune system, the strain of the pathogen. Usually, the duration of the incubation period for lichen black is from 7 days to several weeks, but cases of both faster (2-4 days) and longer development of the disease have been described. In exceptional cases, the hidden period can last for many years – up to 20. Most often, tinea nigra affects children and adolescents, as well as people with weakened immunity and concomitant diseases.
Stage of clinical manifestations
After the end of the incubation period, small (several millimeters in size) foci of black or dark brown color appear on the surface of the skin of the palms, feet, fingers. The Asian version of tinea nigra differs in that such rashes can also appear on the surface of the skin of the forearms, shoulders or trunk. The lesions tend to grow peripherally, as they increase in size, their color changes slightly – they may slightly lighten in the center and remain dark at the edges. Gradually, these spots fuse together, forming areas of irregular (polycyclic) shape – at this stage, it is most difficult to distinguish tinea nigra from malignant melanoma.
As a rule, no subjective symptoms (burning, itching, soreness) are detected with tinea nigra. Lesions, at first glance, do not have a tendency to peeling and skin atrophy, but upon closer examination (under a magnifying glass), you can detect a lag from the surface of the smallest scales. There are no general symptoms (fever, weakness) with tinea nigra, unless they are caused by concomitant diseases. Complications in the form of systemic or deep mycoses have not been recorded even with severe immunodeficiency.
Diagnostics
To determine tinea nigra, the method of dermatological examination is used, as well as microscopic examination of scraping on mushrooms from the lesion. The patient’s medical history should be carefully analyzed, it is highly desirable to prescribe several additional general clinical analyses to determine possible concomitant diseases:
- Collecting anamnesis. When questioning the patient, attention should be paid to his movements – whether he or his loved ones have visited tropical countries in the last few years. It should be borne in mind that the incubation period of black lichen is very long and in some cases may be several years.
- Dermatological examination. On examination, patients with tinea nigra are found to have spots of black or dark brown color on the palms, fingers, feet, sometimes forearms and trunk. The nature, shapes and sizes of foci may vary depending on the stage of development of the disease. In the early stages, these are multiple (rarely single) dark spots of a rounded shape, with a monotonous color and clear contours. With the further development of black lichen, they begin to merge, forming polycyclic formations up to 5-7 centimeters in size. In the center of the hearth, the color saturation decreases somewhat, and on the periphery, on the contrary, it increases.
- Dermatoscopy. Upon closer inspection under a magnifying glass, it can be noticed that there are small scales of skin on the surface of the foci of lichen black, although macroscopically peeling is not determined.
- Laboratory diagnostics. Scraping with a spatula followed by microscopic examination reveals the mycelium of the pathogen against the background of a violation of the processes of keratinization of the epidermis. General clinical tests can reveal any other disease that has weakened the body so much that it has made it vulnerable to the fungus.
Lichen black is similar in its manifestations to some skin tumor processes (pigmented nevus, melanoma), which can cause erroneous diagnosis, especially in countries where this condition is rare.
Treatment
Treatment of black lichen in clinical dermatology is carried out by traditional antifungal agents. Taking into account the fact that this disease is accompanied by disorders of keratinization processes, in order to increase the effectiveness of drugs, the horny layers should be removed before applying them. For this purpose, compresses are used from an alcoholic solution of salicylic acid or hydrogen peroxide. Such pretreatment for lichen black also reduces the risk of relapse, since it softens the horny scales in which the fungus may hide.
After that, local antifungal ointments or creams based on ketoconazole, clotrimazole and other fungicidal preparations are applied to the affected areas of the skin. Given the exclusively superficial skin lesion in lichen black, the use of systemic antifungal drugs does not make sense and is not used. It is important to pay attention to the general condition of the body – to eliminate chronic pathologies, strengthen the immune system, take vitamin complexes. All this also contributes to a faster cure of black lichen.
Forecast
The prognosis for black lichen is favorable, since the disease is eliminated quite easily and quickly by traditional local antifungal therapy. With proper treatment, relapses are extremely rare. However, we should not forget about the high contagiousness of lichen black – after successful therapy, relatives or other persons in close contact with the patient should contact a dermatologist at the first manifestations of pathology. All towels, bed linen and other accessories of the patient with black lichen should be washed in hot water.
Prevention
To prevent this condition, you need to adhere to the rules of personal hygiene when traveling to epidemically dangerous areas (any tropical countries), do not use other people’s things or towels there. Persons who are potentially at risk (suffering from diabetes mellitus, cancer, immunodeficiency) should, if possible, refrain from traveling to countries where black lichen is common.