Chromomycosis is a chronic infectious disease from the group of deep mycoses caused by fungi of certain species and characterized by a long course. A feature of the clinical picture is the lesion of the skin and subcutaneous tissue mainly of the lower extremities with the presence of specific warty growths. Diagnostics is based on the detection of the pathogen in biological material by microscopy, as well as by sowing on nutrient media. Antifungal drugs are used as specific therapy. Additionally, surgical removal of skin outgrowths is performed.
B43 Chromomycosis and pheomycotic abscess
Chromomycosis, chromoblastomycosis or Pedroso’s disease is found everywhere. Sporadic cases are recorded all over the globe, but the population living in countries with humid tropical or subtropical climates, for example, in Brazil, India, Australia, and African countries, is more often affected. People of working age are infected, mainly men 30-50 years old, engaged in tillage or wood and at the same time not wearing shoes. The rarity of chromomycosis among children at this stage is explained by the long incubation period. Pathology occurs regardless of the state of the immune system.
The causative agent is various fungi from the pheogyphomycetes group belonging to the Dematiaceae family: Fonsecaea pedrosoi, Phialophora verrucosa, Fonsecaea compacta. In host tissues, mycosis is rounded dark brown thick-walled cells up to 12 microns in diameter, separated by a transverse partition. These structures are called sclerotic cells and are an invasive form of the fungus.
Pathological agents are quite stable in the external environment, tolerate freezing, and persist for a long time at room temperature. Boiling for 10 minutes, chloramine, formalin has a disastrous effect. In the environment, fungi grow in moist soil, on various plant substrates.
The pathogen enters the body through damaged areas of the skin more often with microtrauma (splinters, minor cuts). Some authors note the possibility of infection through the respiratory tract. In the host’s body, the fungus spreads due to autoinoculation during combing and through lymphatic vessels. Chromomycosis is not transmitted from person to person.
Chromomycosis is limited to the skin and subcutaneous tissue. At the site of infection, there is an active proliferation of epidermal cells, hyperkeratosis. Multiple granulomas and intradermal abscesses are formed. Proliferating structures actively push granulomas onto the surface of the skin, while large growths with a black tinge are formed. Outgrowths tend to ulcerate.
Under microscopy, dark-colored sclerotic cells of the fungus are found in the center of microabsesses. Infiltration by leukocytes, giant and epithelioid cells is noted. Granulomas consist of plasmocytes, lymphocytes, macrophages, fibroblasts, eosinophils. Studies confirm the ability of the pathogen to spread through lymphostructures, which provokes the development of lymphangitis, and with prolonged chronic course – sclerosis of lymphatic vessels.
Chromomycosis is characterized by polymorphism of skin manifestations. Various approaches to the systematization of pathology are used, but the most commonly used clinical classification of the disease, which includes five variants of infection, but does not exclude the simultaneous coexistence of several forms at once or their mutual transformation:
- Nodular. It is characterized by the presence of erythematous papules. In addition, the appearance of small nodules with a smooth or hyperkeratotic surface is noted.
- Tumor-like. Large nodular lesions with a lobular structure are formed. The presence of crusts and scales of brown color, large vegetative formations is possible.
- Warty (verrucose). The rashes resemble vulgar warts. In some cases, the appearance of growths resembling cauliflower is noted on their surface. There is a tendency to ulceration.
- Scaly hyperkeratotic. Foci of infiltration or jagged plaques with clearly defined contours and raised edges of various shapes and sizes. Inclusions in the form of black dots are revealed.
- Scarring, or atrophic. In the center of the elements typical of chromomycosis, cicatricial changes with centrifugal growth appear, due to which the plaques acquire a characteristic ring-shaped or arc-shaped shape. Simultaneously with such rashes, foci without atrophic manifestations can form on the skin.
The incubation period varies from several weeks to several months, sometimes years. The long-term latent and sluggish course of chromomycosis explains the late treatment of patients for medical help. The lower legs and feet, hands are mainly affected, infection of other parts of the body is not excluded. The primary focus is a painless nodule, less often a spot or tubercle of a stagnant red color. These structures, especially spots, have the ability to grow eccentrically, reaching up to 20 cm in diameter.
Then chromomycosis passes into one of its clinical forms. Different variants can coexist on the skin of one patient. More characteristic is the development of warty papillomatous growths that resemble cauliflower, are easily injured, ulcerated, infected. Often they are covered with brownish crusts due to the drying of purulent exudate. Patients complain of discomfort, soreness in the rash, extremities, burning, itching. The healing of foci occurs with the formation of rough scars.
The most common complication is the addition of infection with ulceration of outgrowths. The study of cases of the disease confirms the possibility of damage to internal organs. Bone involvement may resemble the Madura foot syndrome, and the clinic for brain metastases is supplemented with neurological symptoms. Chronic inflammation leads to the formation of lymphedema. The proliferation of fibrous tissue and lymphostasis contribute to the restriction of movements in the extremities. There are studies describing the development of squamous cell carcinoma with a long course of chromomycosis.
During an objective examination, a dermatologist pays attention to the presence of specific elements of the rash and characteristic complaints. The long course is accompanied by the development of lymphostasis of the affected limbs, disfiguring changes. During additional infection, the appearance of purulent exudate, crusts is noted. It is important to collect a detailed history of the disease and clarify the features of the patient’s lifestyle.
The determining method of diagnosis of this pathological condition is the detection and identification of the pathogen. Microscopy of the separated ulcers, scrapings, the study of tissue biopsies is carried out in order to identify tissue forms of the fungus. Sowing the substrate on specific nutrient media gives the growth of characteristic fluffy colonies from olive to dark brown or almost black. Serological reactions have no diagnostic value.
Differential diagnosis should be carried out with other mycoses, for example, paracoccidioidomycosis, North American blastomycosis. It is important to exclude diffuse cutaneous leishmaniasis, tuberculous lesions of the skin, mycetoma. Chromomycosis may resemble elements in psoriasis, changes in tertiary syphilis. Growths can mimic various neoplasms, such as keratoacanthoma and sarcoma.
Chromomycosis refers to infections that are difficult to treat. Complete cure is rare, characterized by frequent recurrence. According to various data, clinical recovery and complete elimination of the pathogen occurs in 15-80% of cases. A long-term intake of antifungal drugs is prescribed. There are no strict time standards, depending on the type of medication, the course lasts from 2 months to complete cure. Intraconazole, amphotericin B, ketoconazole, terbinafine are used.
Therapy should be comprehensive. In order to prevent relapses, the use of drugs is supplemented by the removal of growths. Small lesions can be surgically excised with wide margins. Cryodestruction of foci is possible, but the depth of exposure is not standardized. Thermotherapy is used with local heating of outgrowths up to 42-24 ° C. Curettage is not recommended due to the risk of damage to lymphatic structures.
A good effect in studies was shown by taking triazoles of the 2nd generation: voriconazole, posaconazole, ravuconazole, but sometimes satisfactory results of infection treatment were accompanied by the development of adverse reactions. For example, the use of voriconazole in rare cases was complicated by visual impairment and the development of photosensitive skin reactions. The combination of fluorocytosine and intraconazole proved to be effective. The positive effect was achieved by the use of immunomodulatory drugs glucan and imihimod.
Prognosis and prevention
The prognosis for life is favorable, the neglected course worsens the chances of a complete cure, leads to a decrease in working capacity. The duration of chromomycosis is up to several decades. Involvement of internal organs in the pathological process increases the risk of mortality, and the development of complications contributes to the disruption of limb functions. Methods of specific prevention of infection have not been developed. Measures of non-specific protection include compliance with the rules of personal hygiene and occupational hygiene, the use of personal protective equipment, mandatory wearing of shoes.