What is Tinea Corporis?
Tinea corporis is a skin infection caused by certain types of fungi, known as dermatophytes, which is found all over the world. This infection is named according to where on the body it appears, and can affect areas such as the torso, neck, arms, and legs. There are different names for this type of infection when it shows up on other parts of the body, like the scalp (tinea capitis), the face (tinea faciei), hands (tinea manuum), the groin (tinea cruris), and feet (tinea pedis).
What Causes Tinea Corporis?
Dermatophytes, a kind of fungus, can cause skin infections because they can attach to keratin, a type of protein found in the skin. These infections are commonly called tinea corporis. The dermatophytes that cause tinea corporis belong to three main types: Trichophyton, Epidermophyton, and Microsporum. Among these, Trichophyton rubrum is the most common, accounting for 80 to 90% of all cases in the last 70 years.
Other isolates that can also cause this skin infection include Trichophyton mentagrophytes and Microsporum audouinii. You can typically get this infection from direct skin contact with soil, animals, or another person who is infected.
In some cases, the exact cause depends on how the infection was transmitted. For example, tinea corporis can often result from direct contact with someone who has tinea capitis, a similar infection that affects the scalp. For tinea capitis, the most common cause in the United States and the United Kingdom is Trichophyton tonsurans.
This type of fungus is also commonly found in cases of tinea corporis gladiatorum, which is a kind of infection that often occurs in athletes with a lot of direct skin-to-skin contact, like wrestlers. People who get tinea corporis from close contact with cats or dogs are typically infected with Microsporum canis.
Risk Factors and Frequency for Tinea Corporis
Tinea corporis, a type of skin infection, is quite common everywhere in the world. The infection is mostly caused by a type of fungi called dermatophytes. Conditions like excessive heat, high humidity, and tight clothing can contribute to more severe and frequent infections. Certain groups of people are more vulnerable to this infection. Kids, for instance, are more prone to tinea corporis.
- Tinea capitis and tinea corporis are the most common fungal skin infections in children before puberty.
- Kids are also more likely to get zoophilic infections. These infections are usually caught from animals like cats and dogs.
- People with weak immune systems are also more prone to these infections. Such individuals have a higher chance of developing Majocchi granuloma – a specific kind of tinea corporis that affects the deep layers of skin, unlike the usual infection which affects the surface.
Signs and Symptoms of Tinea Corporis
Typically, patients come in complaining of an itchy, red rash. The rash commonly appears on exposed areas of the body like the neck, trunk, and limbs.
When doctors look at the rash, they usually see single or multiple spots that are round or oval-shaped. These spots, which can sometimes appear as raised patches, have clear-cut edges and might even have small blisters. The redness and swelling of the spots can vary from person to person.
As the rash develops, it spreads out from the center, leaving a clear patch in the middle with some slight flaking. This makes it look like a ring, hence the term “ringworm”.
Testing for Tinea Corporis
Tinea corporis, also known as ringworm, is usually diagnosed by a doctor based on a discussion regarding your symptoms and a physical examination. However, there are also tests that can be done to confirm the diagnosis. One method is to examine skin scrapings under a microscope using a solution called potassium hydroxide (KOH). KOH can help to visualize the long, narrow, branching structures known as hyphae that are characteristic of ringworm. However, up to 15% of the time this method might not show the infection, even if it’s present.
Another option for confirming the diagnosis is a fungal culture. This process involves growing the fungus from a sample in a lab, but it does take a longer time to get results. The fungus may start to grow within five days, but identifying the specific type could take up to four weeks. Hence, a sample cannot be declared as “no growth” until at least four weeks have passed.
The fungal culture typically grows on a special substance called Sabourad dextrose agar. This substance, containing sugar and a type of thickening agent, helps promote the growth of the fungus. The identification of the specific type of fungus is done by examining the shape, color, and surface appearance of the grown culture.
Treatment Options for Tinea Corporis
Dermatophyte infections, also known as fungal skin infections, are usually treated with either topical treatments (applied directly to the skin) or oral medications (taken by mouth).
If you have a localized tinea corporis, which is a type of fungal infection on the body, it is usually treated with a topical therapy that you apply once or twice a day. The treatment usually lasts for two to three weeks. However, the aim of this treatment is to help the symptoms to disappear. It is worth noting that nystatin, which is a commonly used antifungal cream, is not usually effective for tinea corporis.
There are several types of antifungal creams and solutions you could use, such as clotrimazole, ketoconazole, miconazole, naftifine, or terbinafine. Remember, you need to apply these regularly and exactly as directed, for the treatment to be fully effective.
However, in cases where the infection is spread over a large area or the topical treatment hasn’t been successful, you might need to take oral medications. Two commonly used oral treatments are terbinafine and itraconazole. Taking these medications should help clear up the infection within about two to three weeks.
Other possible oral treatments include fluconazole and griseofulvin. The duration and dosage of treatment can vary, but typically ranges from one to four weeks. As with all medicines, it’s important to take them exactly as directed by your healthcare provider. Please consult with them to understand the best treatment strategy for you. Remember, every individual’s case is unique and thus, the best treatment method will vary based on individual conditions.
What else can Tinea Corporis be?
Some diseases can look very similar to ringworm, which is a skin infection caused by a fungus. This group of diseases often show up as ring-like spots on the skin. If a ringworm treatment isn’t working or a microscope doesn’t find any fungus, it’s important for doctors to look into other possibilities. This is especially true if there’s a lot of skin involved, which could indicate a more serious condition.
The following common conditions can often look like ringworm:
- Nummular eczema
- Erythema annulare centrifugum
- Tinea versicolor
- Cutaneous candidiasis
- Subacute cutaneous lupus erythematosus
- Pityriasis rosea
- Contact dermatitis
- Atopic dermatitis
- Seborrheic dermatitis
- Psoriasis
There are also more severe diseases to consider ruling out, which include:
- Secondary syphilis
- Mycosis fungoides
- Parapsoriasis
What to expect with Tinea Corporis
With the right treatment and if patients follow their doctor’s instructions closely, the outlook is usually positive.
Possible Complications When Diagnosed with Tinea Corporis
While complications are rare in skin infections caused by dermatophyte (a type of fungus), one possible issue might be Majocchi granuloma. This is an unusual condition where the dermatophyte enters the skin through a hair follicle and moves deeper, potentially reaching the second layer of the skin or the tissues beneath the skin. Simply activities like shaving can make someone more likely to develop Majocchi granuloma. The infection affects the hair follicles and may cause red lumps or bumps on the skin. In some cases, these can worsen into abscesses, which are painful pockets of pus. Majocchi granuloma can be treated with oral antifungal medication, such as terbinafine 250 mg once a day, for 2 to 4 weeks.
Complications of Dermatophytic Infections:
- Majocchi granuloma
- Red lumps or bumps (erythematous nodules or papules)
- Painful pockets of pus (abscesses)
Preventing Tinea Corporis
Education is key in preventing tinea corporis, which is a type of skin infection caused by fungus. It can be helpful for patients to wear clothes that are light and not too tight-fitting. Keeping the skin clean and dry can also help to prevent this infection from developing.
When starting treatment with a type of medication called a topical antifungal, it’s important for patients to consistently follow the treatment plan. However, it’s worth noting that improvements may not be noticeable right away. Patients may need to be reminded that even with the right treatment, it might take a few weeks before symptoms start to get better.
