|Other names: Ringworm, tinea circinata, tinea glabrosa|
|This patient presented with ringworm on the arm, or tinea corporis due to Trichophyton mentagrophytes.|
|Symptoms||Circular, slightly reddish patch on arms, legs or trunk.|
|Causes||Dermatophytes, most common genera: Trichophyton, Microsporum, and Epidermophyton|
|Diagnostic method||Appearance, microscopy|
|Frequency||20% lifetime risk|
Tinea corporis, also known as ringworm, is a fungal infection (dermatophytosis) of the skin of the arms, legs, and front and back of the chest. It generally presents as a well defined slightly reddish, scaly, circular patch with an edge that appears to be raised and expanding. The centre often looks paler.
Tinea corporis is common. Up to 1 in 5 people will be infected in there lifetime. Males and females are affected equally frequently.
Signs and symptoms
Generally, Tinea corporis appears as enlarging flaky raised red rings with a central area of clearing. It may look oval. Other features of tinea corporis include itching, with loss of hair over the patch and dry and flaky surrounding skin. Similar appearances of ringworm may also occur on the scalp (tinea capitis), beard area (tinea barbae) or the groin (tinea cruris.
Tinea corporis is caused by a tiny fungus known as dermatophytes, usually of the genera Trichophyton (skin, hair, and nails), Microsporum (skin and hair), and Epidermophyton (skin and nails). T. rubrum, T. tonsurans, and M. canis are the most common causes. These fungi normally live on the skin surface, and when the opportunity is right, they can induce a rash or infection. The causative fungi can vary according to which part of the world a person lives in. T. interdigitale, T. verrucosum, T. violaceum, T. concentricum, E. floccosum, M. audouinii, and M. gypseum, can also cause Tinea corporis. Other more rare fungi can also cause the condition.
It can spread from one person to another via direct skin contact. People can acquire Tinea corporis from animals, such as after touching dogs and cats. The condition can occur following contact with other animals such as horses, pigs, ferrets and cows. It can occur by touching non-living objects like personal care products, bed linen, combs, athletic gear, or hair brushes.
People at higher risk of getting Tinea corporis include those who live in crowded humid conditions, sweat excessively, participate in close contact sports like soccer, rugby, or wrestling, those who wear tight clothing or who have a weakened immune system such as HIV or are taking drugs that prevent fighting infection.
Superficial scrapes of skin examined underneath a microscope may reveal the presence of a fungus. This is done by utilizing a diagnostic method called KOH test, wherein the skin scrapings are placed on a slide and immersed on a dropful of potassium hydroxide solution to dissolve the keratin on the skin scrappings thus leaving fungal elements such as hyphae, septate or yeast cells viewable. If the skin scrapings are negative and a fungus is still suspected, the scrapings are sent for culture. Because the fungus grows slowly, the culture results do take several days to become positive.
Because fungi prefer warm, moist environments, preventing ringworm involves keeping skin dry and avoiding contact with infectious material. Basic prevention measures include:
- Washing hands after handling animals, soil, and plants.
- Avoiding touching characteristic lesions on other people.
- Wearing loose-fitting clothing.
- Practicing good hygiene when participating in sports that involve physical contact with other people.
Most cases are treated by application of topical antifungal creams to the skin, but in extensive or difficult to treat cases, systemic treatment with oral medication may be required. The over-the-counter options include tolnaftate, as well as ketoconazole (available as Nizoral shampoo that can be applied topically).
Topical antifungals are applied to the lesion twice a day for at least 3 weeks. The lesion usually resolves within 2 weeks, but therapy should be continued for another week to ensure the fungus is completely eradicated. If there are several ringworm lesions, the lesions are extensive, complications such as secondary infection exist, or the patient is immunocompromised, oral antifungal medications can be used. Oral medications are taken once a day for 7 days and result in higher clinical cure rates. The antifungal medications most commonly used are itraconazole, terbinafine, and ketoconazole.
The benefits of the use of topical steroids in addition to an antifungal is unclear. There might be a greater cure rate but no guidelines currently recommend its addition. The effect of Whitfield's ointment is also unclear.
Tinea corporis is moderately contagious and can affect both humans and pets. If a person acquires it, the proper measures must be taken to prevent it from spreading. Young children in particular should be educated about the infection and preventive measures: avoid skin to skin contact with infected persons and animals, wear clothing that allows the skin to breathe, and don't share towels, clothing or combs with others. If pets are kept in the household or premises, the animal should be checked for tinea, especially if hair loss in patches is noticed or the pet is scratching excessively. The majority of people who have acquired tinea know how uncomfortable the infection can be. However, the fungus can easily be treated and prevented in individuals with a healthy immune system.
Tinea corporis is the commonest dermatophytosis and occurs across the world, particularly hot, humid places. Young adults are most prone, and males and females are affected equally. Up to 1 in 5 people will be infected in there lifetime.
Society and culture
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- MedlinePlus Encyclopedia: Skin lesion KOH exam
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- "Fungus Infections: Tinea". Dermatologic Disease Database. American Osteopathic College of Dermataology. Retrieved 2011-07-19.
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