Ringworm (Tinea Corporis, Tinea Faciei)

What is ringworm?

Ringworm is a rash that is indeed ring-shaped, but it has nothing to do with worms.  It is a common superficial fungal infection that appears as circular scaly patches (Figure 1) on the skin of the trunk, arms, legs, neck, or face.  The medical term for ringworm is tinea corporis when it occurs on the body, and tinea faciei when it occurs on the face.

Figure 1.  Typical ringworm lesions are red circles with raised scaly borders.  Photograph courtesy of Dr. Kenneth E. Greer.

What causes ringworm?

Ringworm is caused by fungi known as dermatophytes, a term derived from the Greek words meaning “skin plants.”  Dermatophytes are filamentous fungi that grow on humans, animals, or in the soil. These fungi live on keratin, a protein found in the outermost layer of human skin, as well as in hair and nails, but are not able to grow through the skin or cause internal disease.

The species that usually cause ringworm are Trichophyton rubrum, Trichophyton tonsurans, and Microsporum canis.  Less commonly, Trichophyton mentagrophytes and Trichophyton verrucosum may also cause ringworm.

Ringworm is a contagious disease.  Most people acquire ringworm from direct contact with another infected individual, but it can be transmitted through contaminated clothing, linens, towels, shoes, furniture, athletic equipment, or personal care items.  It is also possible to catch ringworm from animals such as cats or dogs or from fungus in the soil.  The species that usually live on animals, such as T. verrucosum, tend to cause a more inflammatory (redder, more raised, and itchier) form of ringworm when they infect people than the species that usually live on humans.

Wrestlers and others who engage in contact sports may acquire a widespread form of ringworm known as tinea gladiatorum (Figure 2). It is thought that direct skin-to-skin contact results in transmission of fungus from one wrestler to another, but contaminated mats and headgear have also been blamed.  A study in the 1980s found that 60% of college wrestlers and 52% of high school wrestlers had ringworm at some point during one season.

People who have a fungal infection on one part of the body, such as athlete’s foot (tinea pedis), may spread the infection to other parts of their body, resulting in ringworm.  Likewise, children who have a fungal infection of the hair (tinea capitis) may spread the fungus to their face or body.

Figure 2.  Tinea gladiatorum in a young wrestler.  Photograph courtesy of Dr. Kenneth E. Greer.

Who gets ringworm?

Ringworm occurs in adults and children of both sexes and all races.  This is different from most superficial fungal infections, including athlete’s foot and jock itch, which occur almost exclusively in teenagers and adults.

Risk factors for ringworm include:

• having a superficial fungal infection of the scalp (tinea capitis) or feet (tinea pedis)
• exposure to household members who have superficial fungal infections
• use of shared equipment in locker rooms, gymnasiums, or health clubs
• participation in contact sports such as wrestling
• immunosuppression
• living in a hot, humid climate

What are the symptoms of ringworm?

Ringworm may be itchy or have no symptoms at all.  Affected individuals usually seek medical care because of the appearance of the lesions.

What does ringworm look like?

Ringworm typically appears as a round, pink or red, flat patch or slightly elevated plaque with central clearing and scaly (flaky) or crusted raised borders (Figure 1).  It generally begins as a small round spot that grows outward over weeks to months, forming a ring shape.  Ringworm may occur anywhere on the exposed skin of the trunk, arms, and legs, though in wrestlers, it is most common on the head, neck, and arms.

Ringworm has several variants.  It is not always circular or oval, but may be consist of more wavy, irregular lines (Figures 3 and 4).  There may be multiple circles on one person (Figure 5).  When caused by a fungus that usually infects animals, it may be bright red and raised, or contain pus bumps.  It may be concentrated in and around hair follicles.  When ringworm has been treated with topical corticosteroids, it may resemble other skin conditions such as eczema or psoriasis, making diagnosis difficult.

When ringworm occurs on the arms, legs, or trunk, it is called tinea corporis.  When it occurs on the non-hairy skin of the face, it is called tinea faciei (Figure 6).  Infection of the hair, nails, groin, feet, and hands is not considered to be ringworm and will not be discussed here.

Figure 3.  Ringworm on the ankle has grown into a large irregular shape with scaly borders and central clearing. Photograph courtesy of Dr. Kenneth E. Greer.

 

Figure 4.  A patient with extensive ringworm on the back, forming overlapping rings. Photograph courtesy of Dr. Kenneth E. Greer.

Figure 5.  Multiple ringworm lesions, some with a more scaly appearance and others that are more inflamed. Photograph courtesy of Dr. Kenneth E. Greer.

Figure 6. Ringworm on the face in an adult. Photograph courtesy of Dr. Kenneth E. Greer..

How is ringworm diagnosed?

If a case of ringworm has the classic appearance of a round red rash with clearing of the center and a scaly border, the diagnosis is usually straightforward.  Nonetheless, physicians usually confirm the diagnosis with one of the following diagnostic tests:

1. Potassium hydroxide preparation:  In this test, the physician uses a sharp blade or glass slide to scrape off dead skin cells from the edge of the suspect lesion.  The dead skin cells are collected onto a microscope slide, treated with a solution of potassium hydroxide and heated to digest the cells, then examined under a microscope.  Sometimes, a dye is added to the potassium hydroxide solution to facilitate visualization of the fungal elements.  The physician examines the slide, looking for branching, septated fungal hyphae (Figure 7).  This is the most rapid and inexpensive test for dermatophyte fungi, although it occasionally gives false negative results when an individual has already partially treated their ringworm and few fungal cells are still present.
2. Fungal culture:  The physician scrapes dead skin cells from the edge of a suspect lesion and sends them to a microbiology laboratory.  There, the material is applied to several culture media known to support growth of dermatophyte fungi.  By the appearance of the fungal colonies that grow and their growth characteristics, it is possible not only to show that a fungus was present, but also to determine the species.  However, this method takes 2-3 weeks to give results and also frequently gives false negative results.  Furthermore, it is not usually necessary to know the exact species in order to treat ringworm.
3. Skin biopsy:  When a case of ringworm looks very similar to other skin diseases and a potassium hydroxide preparation is negative or inconclusive, physicians will sometimes take a small sample of skin for pathologic examination.  Under local anesthesia, a small plug of skin called a punch biopsy is removed and fixed in formalin.  Pathologists examine the skin after slicing it into thin sections and staining it with dyes that highlight fungal elements.  This method is most expensive (and slightly uncomfortable for the patient), but it does usually give definitive diagnostic results.

Figure 7.  A potassium hydroxide preparation demonstrating branching fungal hyphae typical of a dermatophyte fungus.  The arrows point to fungal elements. 

What other conditions could be confused with ringworm?

Ringworm on the body or limbs may be confused with several skin conditions, but they can usually be distinguished based on the appearance of the lesions or diagnostic testing:

• Nummular eczema:  This form of eczema appears as round or ring-shaped patches, usually on the limbs, and is more common in the winter. 
• Psoriasis:  This skin disease may have raised pink scaly plaques on the trunk and limbs, but unlike ringworm, psoriasis is usually symmetrical and occurs on bony prominences, like the knees, elbows, and shins.
• Subacute lupus erythematosus:  This is a relatively rare skin condition that may look like red rings with raised borders, but it is usually confined to the sun-exposed skin of the chest, arms, and face, unlike ringworm, which can occur anywhere.

Ringworm on the face (tinea faciei) has a slightly different appearance and can be confused with the following:

• Seborrheic dermatitis: This rash consists of symmetrical pink scaly patches in the eyebrows, skin folds next to the nose, and on the scalp.  
• Perioral dermatitis:  This rash appears as tiny, scaly bumps around the mouth, nose, and eyes, rather than scaly circular patches.
• Contact dermatitis:  This rash appears as red, scaly or crusted, itchy patches.
• Acne:  This common facial eruption consists of blackheads, whiteheads, pimples, pustules, nodules, and cysts, rather than the scaly patches with occasional pus bumps seen in ringworm.
• Rosacea:  This condition appears as symmetrical redness and dilated blood vessels on the cheeks, nose, forehead, and chin, with occasional pimples.  Unlike ringworm, it is not usually scaly (flaky).

Ringworm can be distinguished from each of the conditions listed above by doing a skin scraping and potassium hydroxide preparation (Figure 7) or fungal culture.  These tests would be expected to show evidence of dermatophyte fungi in ringworm and be negative in all the other diseases. 

How can one prevent ringworm?

The best way to prevent ringworm is to avoid physical contact with individuals who have any type of fungal infection of the skin.  Since the species of fungi that cause athlete’s foot and tinea capitis can also cause ringworm, it is important to treat these fungal infections in order to prevent their spread to other body areas.

In addition to avoiding direct contact with individuals who have ringworm, it is also wise to avoid sharing clothing or equipment such as hats, helmets, or gym mats without sanitizing them between users. 

Because ringworm has reached epidemic proportions among wrestlers, most leagues require sanitization of mats, inspection for ringworm lesions prior to competition, covering lesions during practices, and treatment for at least one week before a wrestler can return to competition.

Since fungi prefer to grow in a warm moist environment, showering after exercise and changing into clean dry clothing can be helpful in preventing ringworm.

How is ringworm treated?

Ringworm can usually be cured with topical antifungal creams, several of which are available over-the-counter (OTC).  These creams should be used twice daily until the rash has resolved and then continued for an additional 7 – 14 days in order to prevent recurrence of the infection.  If you suspect you have ringworm, but find that it does not improve as expected with one of the following medications, it is important to see a doctor to confirm the diagnosis and obtain appropriate treatment.

The following topical medicines are effective for ringworm:

• Clotrimazole 1% cream (OTC)
• Miconazole 1% cream (OTC)
• Butenafine 1% cream
• Econazole nitrate 1% cream
• Terbinafine 15 cream
• Ketoconazole 2% cream

Certain types of ringworm may be more difficult to treat, including those that have previously been treated with topical corticosteroid creams and those involving the hair follicles.  In cases that do not respond to topical antifungal creams, oral antifungal tablets or capsules are required.  Physicians prescribe a particular medication and dose based on the patient’s age, weight, and any other medical conditions they may have.

The following oral medicines are effective for ringworm:

• Terbinafine 250 mg daily for 2 weeks
• Itraconazole 200 – 400 mg daily for 1 week
• Fluconazole 150 – 300 mg weekly for 4 to 6 weeks
• Griseofulvin microsize 5 mg per pound (11 mg per kilogram) of body weight (up to 500 mg) daily for 4 weeks

Is ringworm a serious condition?

Since the fungi that cause ringworm live on keratin protein found in the outer layer of the skin, the hair, and the nails, they cannot invade deeper tissues and cause serious illness.  Nonetheless, ringworm can be very uncomfortable and unsightly, prompting affected individuals to seek medical treatment.  Since ringworm is very common and quite contagious, it is important to treat from a public health perspective.

Most cases of ringworm resolve after treatment without scarring or other residual effects.  It is common for ringworm to recur, however, particularly in people who are frequently exposed to dermatophyte fungi, as would be the case for wrestlers.

More information

Book Chapters

Sobera JO, Elewski BE.  Chapter 77:  Fungal Diseases, pp. 1171-1198.  In Bolognia JL, Jorizzo JL, Rapini RP, eds. Dermatology, volume 1, Mosby, New York, 2003.

Habif TP.  Tinea of the body and face, pp. 374-377, in Clinical Dermatology, Third edition.  Mosby, St. Louis, 1996.

Verma S, Heffernan, MP.  Chapter 188. Superficial fungal infection: dermatophytosis, onychomycosis, tinea nigra, piedra, pp 1807-1821 in Wolff K, Goldsmith LA, Katz SI, Gilchrest BA, Paller AS and Leffell DJ, eds. Fitzpatrick’s Dermatology in General Medicine, Seventh Edition, Volume 2.  McGraw Hill Medical, New York, 2008.

Web Resources

http://www.webmd.com/skin-problems-and-treatments/tc/ringworm-of-the-skin-topic-overview
http://www.emedicine.com/derm/TOPIC421.HTM
http://www.emedicine.com/derm/TOPIC740.HTM
http://www.medscape.com/viewarticle/563197

References

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Alston SJ, Cohen BA, Braun M.  Persistent and recurrent tinea corporis in children treated with combination antifungal/corticosteroid agents.  Pediatrics. 2003; 111:201-203.

Elewski BE, Elgart ML, Jacobs PH, Lesher Jr. JL, Scher RK.  Guideline of care for superficial mycotic infections of the skin: Tinea corporis, tinea cruris, tinea faciei, tinea manuum, and tinea pedis.  J Am Acad Dermatol.  1996; 34(2):282-286.

Fernandes NC, Akiti T, Barreiros MGC.  Dermatophytoses in children: Study of 137 cases.  Rev Inst Med Trop S Paulo.  March-April 2001; 43(2):83-85.

Foster KW, Gahannoum MA, Elewski BE.  Epidemiologic surveillance of cutaneous fungal infection in the United States from 1999-2002.  J Am Acad Dermatol.  2004; 50:748-752.

Kenna ME, Elewski BE.  A U.S. epidemiologic survey of superficial fungal diseases.  J Am Acad Dermatol.  1996; 35:539-542.

Sethi A, Antay R.  Systemic antifungal therapy for cutaneous infections in children.  Pediatr Infect Dis J.  July 2006; 25:643-644.

Singal A, Pandhi D, Agrawal S, Das S.  Comparative efficacy of topical 1% butenafine and 1% clotrimazole in tinea cruris and tinea corporis: a randomized, double-blind trial.  J  Derm Treatment. 2005; 16:331-335.

Vander Straten MR, hossain, MA, Gannoum MA.  Cutaneous infections: dermatophytosis, onychomycosis and tinea versicolor.  Infect Dis Clin N Am. 2003; 17:87-112.