Dermatomycoses . Etiology. Pathogenesis. Clinical features. Diagnostics. Treatment. Prevention

LESSON 9

Dermatomycoses. Etiology. Pathogenesis. Clinical features. Diagnostics. Treatment. Prevention

Theme urgency

Dermatomycoses take second place after pyodermas in the general structure of dermatological disease incidence, which is just what determines the urgency of their study and the organization of their control.

The main group of pathogenic fungi is formed by lower plant microorganisms forming branching double-contour threads of mycelium (measuring to 40-50 µm and more in length and 1 to 6 µm in thickness) and multiplying by means of spores. They parasitize in the soil, on plants, and in animals and man. These fungi are subdivided into large groups: anthropophilic fungi, which only parasitize on the human skin and its appendages, and zooanthropophilic fungi, which parasitize on human and animal skin and its appendages.

Infection with fungi occurs either directly from a sick human or animal, or through various objects and belongings of sick persons or objects used in the care of animals. Some fungus diseases (superficial trichophytosis, microsporosis, etc.) prevail among children of kindergarten age and schoolchildren, others (epidermophytosis, rubromycosis, deep systemic mycoses, etc.) are prevalent among adults. Some fungus diseases are characterized by mass seasonal infection (e.g. high incidence of infection with M. lanosum in the autumn and high incidence of zoophilic trichophytosis in the summer) and seasonal character of exacerbation of the process (e.g. tinea pedis, or ringworm of the feet, in the spring and summer). The climate and soil conditions of the given locality have an effect on the spread of dermatomycoses. This explains the geographic features of the spread of some of these diseases. All this has to be taken into account in elaborating rational measures for the control of dermatomycoses in different regions.

Concrete Objectives:

Students must know:

1. Classification of dermatomycoses.

2. Etiology, epidemiology, pathogenesis of dermatomycoses.

3. Clinical features of dermatomycoses.

4. Investigations of dermatomycoses.

5. Differential diagnosis of dermatomycoses.

6. Treatment of dermatomycoses.

7. Prophylaxis of dermatomycoses.

Students should be able to:

1. To collect the medical history of patient with dermatomycoses.

2. To diagnostic dermatomycoses in patient in typical case.

3. To prescribe the treatment for patient with dermatomycoses in typical case.

4. To recommend preventive measures for patient with dermatomycoses.

5. To carry out Wood's lamp examination.

Tasks for self-study during preparation for lesson.

3.1. Theoretical questions for the lesson:

1. The etiology, epidemiology, pathogenesis, clinical picture, investigation, treatment and prevention of tinea inguinalis.

2. The etiology, epidemiology, pathogenesis, clinical picture, investigation, treatment and prevention of tinea pedis.

3. The etiology, epidemiology, pathogenesis, clinical picture, investigation, treatment and prevention of rubromycosis.

4. The etiology, epidemiology, pathogenesis, clinical picture, investigation, treatment and prevention of trichophytoses

5. The etiology, epidemiology, pathogenesis, clinical picture, investigation, treatment and prevention of microsporosis.

The subject-matter:

DERMATOMYCOSES

Epidermophytosis (Epidermophytia)

Epidermophytosis is a contagious disease of the superficial layers of the smooth skin and the nail plates caused by fungi of the genus Epidermophyton. The hair is not involved. Two clinical forms of epidermophytosis are distinguished: epidermophytosis of the large folds, or epidermophytosis (tinea) inguinalis, and epidermophytosis of the feet, or tinea pedis.

Rubromycosis of the Feet

The foot is the most common localization of the disease. The lesions appear first in the interdigital folds all of which, or almost all, are involved (as distinct from epidermophytosis). The process then extends to the skin on the soles which becomes infiltrated, dry, and diffusely hyperemic, the skin furrows are clearly seen and are marked by furfuraceous scaling. The process also spreads to the sides and dorsal surfaces of the feet and toes. Affection of the skin on the feet leads sooner or later to involvement of the nail plates in the process as a rule. In other cases, the process begins with affection of the nail plates and then spreads to the skin on the feet.

Generalized Rubromycosis

In most patients, generalized rubromycosis develops after a more or less long existence of a localized affection of the skin on the feet (sometimes on the hands too) and of the nail plates. Abnormalities of the internal organs and the endocrine and nervous systems, trophic changes of the skin, and long-term medication with antibiotics, steroid and cytostatic agents predispose to dissemination of the process.

Clinical picture and course. The clinical picture of the disease is diverse and can be conditionally subdivided into several varieties: erythemo-squamous (superficial), follicular-papular (deep), and exudative forms, and affections of the type of erythroderma.

Erythemo-squamous foci of rubromycosis may be found on any skin areas, are attended with severe itching. From the standpoint of clinical diagnosis, the tendency of the foci to gather in groups, to form rings, arches, semi-arches and garlands, the hyperpigmentation and mild scaling in the centre help in suspecting mycosis. Particular importance in the diagnosis is attributed to the scalloped contours of the foci and the interrupted swollen ridge on the periphery. The process takes a chronic course with a tendency to become exacerbated in the warm season.

The follicular-papular (deep) form of rubromycosis usually attacks the legs, buttocks, and forearms. The lesions tend to form figures.

The touching skin in the inguinal and intergluteal areas and under the mammary glands are rather frequent sites of the disease. The surface of the foci is yellowish-red or brown. They are slightly infiltrated and there is scaling. The edges are elevated and have an interrupted scalloped swelling on which small papules and crusts are seen.

In rubromycotic erythroderma, the foci of affection have a deep-red colour with a bluish tinge. They merge and extend over large skin areas. Exudative manifestations of mycosis are relatively rare and may occur in the skin folds and on the limbs.

Treatment. In lesions on the smooth skin of only the palms and soles, treatment is begun with the application of Arievich's keratolytic ointment or varnishes (e.g. Ac. salicylici, Ac. lactici aa 10.0, Collodii elastici 80.0). The keratolytic ointment is applied to the focus under a compress dressing for 48 hours after which 5 per cent salicylic petrolatum is applied under the compress for another 48 hours. As a result of this the horny layer is macerated as a rule and is easily separated (removed with a scalpel or a pair of scissors) in the form of a 'glove' or 'sock'. The keratolytic varnish is applied to the skin on the soles and palms daily for three to five days and no dressing is needed. After that, hot hand or foot baths with potassium permanganate or sodium hydrocarbonate are taken and the remnants of the varnish and the separated horny layer are removed. The procedure is repeated until the hyperkeratotic masses are removed (two or three procedures are sometimes carried out one after the other). Next, the skin is painted with 2 per cent iodine tincture in the morning and with 10-15 per cent sulphur ointment and 2-3 per cent tar or Wilkinson's ointment (for three weeks).

Lesions on the large skin folds and the foci of affection in other forms of generalized rubromycosis are painted with Castellani's paint, 2 per cent iodine tincture, fungicidal ointments. In the generalized forms of rubromycosis and sometimes in cases with localized foci, it is important to reveal the pathogenic mechanisms of the disease and undertake the appropriate treatment. All forms of rubromycosis following a torpid course are managed by non-specific stimulation therapy: injection of imunofan, pyrogenic agents (pyrogenal, prodigiosan), aloe.

The treatment of fungus-infected nails is difficult. Much patience and persistence are required of the patient himself. However, recurrences and reinfections are frequent unfortunately, which is linked with various causes (persistence of the fungus on one nail plate or nail bed leads to the spreading of the process to the 'prepared soil', high prevalence of Epidermophyton and Trichophyton rubrum in nature in high susceptibility to the disease of a person who has recovered from it, etc.).

Oral Lamisil (terbinafin) or Orungal are most effective. Lamisil is prescribed 250 mg daily for 2 months (nails of the hands) and for 3 months (nails of the feet). External therapy is not produced.

Combination of oral griseofulvin with external therapy is prescribed. In some cases, griseofulvin is given at the same time that the nail plates are removed, but usually it is given after all the affected nails and the subunguinal keratotic masses have been removed.

The nail plates are removed by means of keratolytic plasters, (ureaplast, a plaster containing 20 per cent urea; a plaster containing 10 per cent trichloroacetic acid, etc.), keratolytic ointments or surgically with subsequent treatment of the nail bed with fungicidal agents. A thick layer of plaster is applied to the nail plate and covered with adhesive plaster. This dressing is left for 48 hours. The procedure is repeated two to four times until the nail plate becomes soft, after which it is removed with a scalpel or nippers. In removing the nail plate by means of potassium iodide ointment (Araviisky's method), the nail is covered with a thick layer of the ointment over which compress paper and cotton are applied and fastened with a bandage. The dressing is changed several times every four or five days until the nail plate becomes soft and can be removed painlessly with forceps or a scalpel.

With the nail plate removed, treatment of the nail bed with fungicidal agents (nitrofungin, 5 per cent iodine tincture, sulphur-tar ointments, Castellani's paint, etc.) is begun and oral griseofulvin is given at the same time. The adult doses of griseofulvin are as follows: one tablet taken four times a day in body weight less than 60 kg, five times a day in body weight of 60 to 70 kg, six times a day in body weight of 70 to 80 kg, seven times a day in body weight of 80 to 90 kg and eight times a day in body weight over 90 kg. Griseofulvin is taken daily for the first month of treatment and every other day for the next two or three months. It may cause side effects and complications (headache, dizziness, gastro-intestinal disorders, skin eruptions of various character, etc.). Urinalysis and differential blood count must be regularly made during the treatment.

After removal of the nail plates treatment may also be continued by application of 15 per cent resorcin-lactic-salicylic ointment for 48 hours three times running. The ointment is covered with compress paper, cotton and bandage. Next 5 per cent salicylic ointment is applied in the same manner for 48 hours after which the remaining nail plate (the 'root' of the nail) and the keratotic masses are removed. The nail bed is then treated with the fungicidal agents listed above. Whenever necessary, application of keratolytic plasters and dressings with 15 per cent resorcin-lactic-salicylic ointment is repeated.

Trichophytoses

The group of trichophytoses includes three forms of the disease: superficial, chronic, and infiltrative-suppurative, or zoophilic trichophytosis. In each of these forms only the scalp, or the smooth skin, or (less frequently) the nail plates may be involved. Some patients have combined lesions, e.g. affection of the scalp and smooth skin, affection of the scalp, the smooth skin, and the nail plates, etc.

Etiology. Superficial and chronic forms of trichophytosis are caused by the same causative agents, which are called anthropophilic fungi. They are characterized by the fact that they parasitize only on human skin and its appendages, in involvement of the hairs they are localized within the hair shaft ( Trichophyton endothrix ), and cause mild inflammatory changes of the skin. This group of fungi includes T. violaceum and T. tonsurans (crateriforme). Infiltrative-suppurative, or zoophilic, trichophytosis is caused by zooanthropophilic fungi. They are characterized by the possible occurrence both in animals (mice, rats, rabbits, guinea pigs, cows, calves, horses, etc.) and in humans. In affection of the hairs, these fungi are found on the surface of the hair shaft ( T. ectothrix ) and produce an inflammatory reaction on the skin, ranging in intensity from mild to violent with involvement of the subcutaneous fat in the process. This group of fungi includes T'. mentagrophytes (a variant of T. gypseum ) and T. verrucosum (faviforme). When the species of the causative agent in the given patient is known, adequate therapy will be applied and the epidemiological measures will be scientifically substantiated.

Epidemiology. Infection with anthropophilic fungi occurs from direct contact with a sick individual or through articles of everyday use (combs, hats, scarfs, hair-clippers, etc.) and objects (toys, pillow-cases, etc.) contaminated with fungi. Children acquire superficial trichophytosis from other children who have this form of the disease or from adults (mother, grandmother, and others) with chronic trichophytosis of adults. Infection with zooanthropophilic fungi is transmitted by persons sick with the corresponding disease, through contaminated articles or from animals suffering from trichophytosis (calves, horses, etc.), and through scales and hairs left by animals, e.g. on hay, straw, and other objects.

Superficial Trichophytosis

Superficial trichophytosis is most common among schoolchildren but may be encountered at any age. It is not only a 'school' infection, as it was thought to be previously, but a 'family' infection. That is why preventive measures in this mycosis are conducted both in children's establishments (nurseries, kindergartens, schools) and in the family (home) of the sick child.

Clinical picture and course. Superficial trichophytoses of the scalp, smooth skin, and nails are distinguished.

Superficial trichophytosis of the scalp (Trichophytosis capitis) occurs as microfocal and macrofocal varieties differing from each other only in the size of the foci. There is no acute inflammation, the foci have irregular, unclear boundaries, a spherical shape, and are covered with whitish furfuraceous scales. Vesicles, pustules, and crusts may sometimes be found on the periphery of the foci. Not all the hairs in the focus are involved in the process, it is as if there is thinning of the hair (they become rare). Some are broken off very short ( 1-2 mm from the skin surface) and have the appearance of commas, hooks, question marks and are called stubs. Several foci are usually found on the skin, though in some cases there may only be one small or large focus. The patients have no subjective complaints. Adult males may have superficial trichophytosis of the beard and moustache areas (trichophytosis barbae) the clinical manifestations of which are similar to those of trichophytosis of the scalp.

Superficial trichophytosis of the smooth skin mostly occurs on the face, neck, forearms, and trunk, though it may develop on any other skin areas. The foci are clearly circumscribed and are rather elevated above the skin surface. They are round or oval with a small ridge of a macular or papular character on the periphery on which small vesicles and crusts may form. The centre of the focus is marked by resolution of the pathological process and because of that it is paler in colour and peels. The foci merge and form a quaint pattern. Mild itching may sometimes be felt. The downy hair may be involved in the process, which delays recovery. Trichophytosis of the smooth skin is mostly encountered among children.

Trichophytosis of the nails (trichophytosis unguium). The nail plates (usually the finger-nails) are involved in the process in 2-3 per cent of patients with superficial trichophytosis. The lesion first appears on the free margin of the nail (less frequently on the lunula) and spreads over the whole nail within a few months. The nail plate thickens, becomes loose and crumbles, and acquires a dirty-greyish colour. Subunguinal hyperkeratosis develops. Several nail plates are usually involved. If not treated, the process persists for years.

Chronic Trichophytosis

Etiology. The disease is caused by the same anthropophilic fungi which are responsible for superficial trichophytosis.

Pathogenesis. The disease sets in childhood at first as the superficial form which later acquires the features of chronic (black-dot) trichophytosis in girls; most boys recover spontaneously by the time of puberty. Endocrine disorders, disorders of the vegetative nervous system (acrocyanosis), etc. are important in the pathogenesis of the disease. Females account for 80 per cent of all cases. Adults with chronic trichophytosis account for at least 30 per cent of patients with trichophytosis capitis.

Clinical picture and course. Chronic trichophytosis of the scalp, the smooth skin, and the nails are distinguished.

Chronic trichophytosis of the scalp is mostly localized in the occipital and temporal areas where small pale-reddish lesions with a bluish tinge, diffuse or microfocal scaling, and atrophic bald spots are found. A very characteristic feature is involvement of the hairs, which are broken off on a level with the smooth skin and resemble comedones ( blackheads ). They are so characteristic of chronic trichophytosis of the scalp that the disease itself is often called black-dot trichophytosis.

Chronic trichophytosis of smooth skin differs markedly from the superficial form of the disease in clinical picture, localization, and course. Localization of the foci on the skin of the legs, buttocks, knees and forearms is most typical; less frequently they are found on the face and trunk. The foci have no clear-cut boundaries and are continuous with normal skin. They have a cyanotic bluish colour and are covered with scales on various areas, thus resembling foci of chronic eczema. The persistent and torpid course of chronic trichophytosis of the smooth skin is explained by the anergic immunological state of the body and the simultaneous involvement of the downy hairs in the foci, the scalp and the nails (disseminated affection). Subjective disorders are either absent or are manifested by mild itching. Chronic trichophytosis of the skin on the palms and soles is marked by lamellar scaling of the type of dry dyshidrosis, occurring against the background of hyperkeratosis, with frequent involvement of the nail plates and mild inflammation.

Involvement of the nails is encountered in one third of patients with chronic trichophytosis and is characterized by thickening of the nail plates. They become dirty-greyish and uneven and crumble and break easily. The free nail margin separates from the nail bed.

Microsporosis

Etiology. The causative agents of microsporosis, like the causative agents of trichophytosis, are subdivided into two groups, the anthropophilic and zooanthropophilic fungi. Microsporum ferrugineum and M. audouini are anthropophilic fungi which parasitize only on the human skin and its appendages. M. lanosum (" furry or cat" microsporum, syn. M. canis, or 'dog' microsporum) is the only zooanthropophilic microsporum found in Ukraine. The difference in the terminology is explained by the fact that the main source of zooanthropophilic microsporosis in Ukraine are kittens and cats, whereas in European countries it is mostly transmitted by dogs.

Epidemiology. Infection with anthropophilic microsporum occurs during direct contact with a sick person or through clothes and articles used in everyday life, which are contaminated with the fungi. M. ferrugineum is the most contagious among all known pathogenic fungi. With the appearance of a sick child in the collective, many children become infected. The zooanthropophilic microsporum (lanosum) is acquired from a person sick with the disease" (a rare occurrence) or directly from sick kittens, cats, and dogs.

Infection may also occur through clothes and articles (toys, pillow-cases, scarfs, hats, etc.) contaminated with the fungus. It has recently been established that cats may be mycocarriers.

Microsporosis mainly attacks children. By puberty the disease may be cured spontaneously. In adults, only the smooth skin is involved. Microsporon does not affect the nail plate as a rule.

Clinical Picture and Course of Microsporosis caused by anthropophilic M. Ferrugineum

Affection of the scalp is marked by the appearance of very many small foci with irregular outlines and unclear boundaries, which resemble the lesions in superficial trichophytosis. Unlike the latter, however, in anthropophilic microsporosis the foci tend to coalesce and form one large focus of affection with polycyclic edges, moderate scaling, and a cyanotic-pink colour. This form of microsporosis is characterized by the localization of the foci in marginal zones: some are on the smooth skin and others on the scalp. Often foci are arranged in the form of iris, i.e. one of the rings (the hyperemic ridge of swelling) seems to be arranged within another, sometimes forming quaint patterns. The regularly found well pronounced follicular hyperkeratosis in the foci of affection on the scalp is a clinical symptom distinguishing the disease from superficial trichophytosis and zoophilic microsporosis of the scalp. A characteristic feature of all forms of microsporosis is that the affected hairs break off long ( 5-8 mm from the skin surface) and that there is a whitish muff at the base of the hair shaft. All the hairs are affected in the focus.

The foci on the smooth skin are well outlined and often produce quaint figures and iris forms. M. ferrugineum often causes isolated affection of the smooth skin without involvement of the scalp in the process but with affection of the downy hair, as a result of which it is difficult to cure a patient.