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Tinea corporis

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What is Tinea corporis

Tinea corporis also known as ringworm infection, tinea circinata or tinea glabrosa is a skin fungal infection that affects the skin of the trunk, arms, legs or neck but does not appear on the feet, hands, scalp or the groin area.

Epidemiology:

the transmission of the pathogens occurs by direct contact with an infected person or animal, by contact with an item that contains infected particles of skin or by spreading it from one’s feet that have been previously affected. In children, the most common way of getting the disease is by touching animals. Fungi affect both males and females and the prevalence peaks in the pre-adolescent children.

There are some environmental factors that predispose to the infection and are typical for fungi. They include worm, moist climates and wearing tight-fitting, occlusive clothing. Small injuries and frequent skin-to-skin contact favours the invasion of the pathogens. Such conditions are encountered in those who practice contact sports (wrestling for example) and are often called Tinea corporis gladiatorum. It occurs most commonly on the head, neck or arms.

What causes ringworm infection

Aetiology of the infection: the disease can, in fact, be caused by any dermatophyte (fungi that infect the skin) but is most commonly attributed to the next species: Trichophyton rubrum, Epidermophyton floccosum, Trichophyton interdigitale, Microsporum canis (found on cats and dogs), Trichophyton tonsurans and Trichophyton concentricum (this one, however, is limited to the Far East, the South Pacific and South and Central America).

How does Tinea corporis look

Usually, there is a circular patch with a red, scaly, a bit raised border. With time, the changes progress outwards and show a almost complete central clearing with some scaling. The ring-shaped lesion can be one or they might be multiple. The types of fungi which have been contracted from animals usually show a more pronounced immune response.

A very broadly spread disease can be the first sign of AIDS or it might follow the use of topical corticosteroids (anti – inflammatory drug).

Tinea corporis can be acute or chronic (mild disease which persist for a long time).

Differential diagnosis: ringworm infection can sometimes look a lot like nummular eczema, psoriasis, tinea versicolor, infection with candida, lupus erythematosus or different types of dermatitis (contact, atopic, seborrhoeic).

Diagnosis: beside its typical appearance, the doctor might have to scrape a bit the border of the lesion and examine the specimen under a microscope. In cases, where the diagnosis of ringworms is suspected but cannot be proven otherwise, the specimen can be put in a culture medium and in about a week or two, the organism should show signs of growth.

How to treat ringworm infections

Treatment: with localised disease, topical anti fungal drugs are usually effective enough. Typically, they have to be applied twice daily for about two to four weeks (but the regimen depends on the drug) and another seven days after the symptoms have disappeared. If the disease has spread to a larger area, if there is involvement of the hair follicles or if the infection does not respond to topical treatment, systemic anti-fungal agents have to be taken.

Other forms of tinea corporis:

  • Fungal folliculitis (infection of the hair follicles): also called Majocchi granuloma is a deeper form of tinea corporis which can resemble a carbuncle (localized skin infection from which pus can be passed) or kerion (a very nasty form of ringworm of the scalp). It’s usually caused by Trichophyton rubrum or Trichophyton mentagrophytes and shows up in places where hairs have been shaved. In patients with a compromised immune system (cancer, AIDS etc.), lesions appear to be even more deeply located and nodule-like. Orally taken medications are necessary in order to cure this type of infection.
  • Tinea incognito: is a term which describes a ringworm infection of the skin which has been previously treated with corticosteroids because it was mistaken for another dermatological disease. Because of this treatment, lesions do not appear as typical as always and a biopsy is sometimes in order. Systemic anti fungal treatment is usually indicated.

Prognosis: cure rates for ringworm infection of the body are very good. Most of the times, topical treatment cures all the symptoms of the disease. If other parts of the body are infected (like nails or feet) they should be cured in order to prevent the tinea to reoccur.

How to avoid ringworms

Prevention: avoid sharing objects of personal hygiene (like towels, combs etc.), having close contact with infected people or animals, wash hands with hot water and soap after petting animals. All the pets should be checked for ringworms and treated if they have it.

References

Arnold, Harry L, Odom, Richard B, James, William D and Andrews, George Clinton, 1990, Andrews’ diseases of the skin. Philadelphia : Saunders.

Fitzpatrick, Thomas B and Freedberg, Irwin M, 2003, Fitzpatrick’s dermatology in general medicine. New York : McGraw-Hill, Medical Pub. Division.

Rook, Arthur and Burns, Tony, 2010, Rook’s textbook of dermatology. Chichester, West Sussex, UK : Wiley-Blackwell.

Wolff, Klaus, Johnson, Richard Allen and Fitzpatrick, Thomas B, 2009, Fitzpatrick’s color atlas and synopsis of clinical dermatology. New York : McGraw-Hill Medical.

http://en.wikipedia.org/wiki/Tinea_corporis

http://www.merckmanuals.com/professional/dermatologic_disorders/fungal_skin_infections/tinea_corporis.html

http://www.dermnetnz.org/fungal/tinea-corporis.html

http://emedicine.medscape.com/article/1091473-followup#showall

 

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