Nerdy Science Blog

Jock itch (Tinea Cruris) is a superficial fungal infection of the groin area. It can be caused by different microorganisms, the most common being Trichophyton rubrum and Trichophyton mentagrophytes. It is characterized by the development of well-marginated, erythematous, half-moon-shaped plaques in those folds that spread to the upper thighs. The border of the lesion is well defined, usually present itself with fine scaling or vesicular eruptions. The lesions are usually bilateral and do not include scrotum or penis but has the ability to migrate to other places of the body like to the perineum, perianal area, and even onto buttocks in chronic cases.

There are few risks factors that could promote the growth of Tinea Cruris. These include increased sweating during summer, wearing wet clothes, wearing multiple layers of clothing, depressed immune response (for people with AIDS or atopy) and obesity. Fungal grow and reproduce when the conditions allow them to. Wet and moist surface promote such possibility and even thou tinea cruris response well to medication, it is best to prevent it from happening at all.

The cause of such infection is usually due to patient’s own tinea pedis (Athlete’s foot). Thus, it is quite common for both of the condition to present in one patient. Patients who scratch their foot when it is itchy due to tinea pedis, bring the fungal up to their groin where the spores stay on their hands. Thus, if you are having tinea pedis, avoid scratching them too much and always wash your hands!

At first, the patient might not have any complains as the lesions could be asymptomatic. This causes patients to pay less attention on the lesion. But when time goes by, the lesions are often itchy or pruritic. Acute condition such as sudden inflamation of that area may result from wearing occlusive clothing. Itch usually causes patient to scratch the affected area, thus result in an ecazematous reddish appearance. If topical steroids are applied, it may alter the appearance of the lesion, causing a more extensive eruption with irregular border, thus making the diagnosing process harder and more challenging.

Usually, fungal culture will be use to help diagnose this condition. The fungus will be taken from the affected area of the patient and will be grow in laboratory condition using Sabouraud’s dextrose agar or by using dermatophyte test medium. Another faster method is the potassium hydroxide preparation of skin scrapings from the border of the lesions. It will shows translucen, branching, rod-shaped hyphae which is characteristic for Trichophyton rubrum. Both of these methods are based on skin biopsies. Finding hyphae in epidermis is the best way to confirm the diagnosis.

It is important to differentiate jock itch with other conditions that could present with the same sign and symptoms.

Intertrigo – This is an inflamatory process of moist opposed skin folds. Usually the causes of such infection include bacteria, yeast and fungi. The main difference of Intertrigo and jock itch is patients with Intertrigo has a characteristic painful longitudinal fissures which occurs in creases of skin fold.

Erythrasma – This is a diffuse brown, scaly, noninflammatory plaque with irregular borders which often involve the groin. The cause of such lesion is usually bacteria – Corynebacterium minutissimum. With the examination of Wood’s lamp, the lesion fluoresces in a coral-red colour.

Other conditions that you should rule out are Seborrheic dermatitis, Psoriasis of groin, Candidiasis of groin and Acanthosis nigricans.

General measures can be adapted to help to prevent jock itch. Avoid predisposing conditions that could increase the moisture of the skin. Avoid hot baths and tight-fitting clothing that usually could trap a lot of moist in areas, especially the groin. Try wearing boxer shorts instead of briefs. Try to keep the area as dry as possible by using talcum powder. These powder absorb moisture effectively, slowing down the reproduction and growth of the fungi. Topical steroid should not be use as it might promote another condition called Tinea incognito. Besides such measures, there are no restrictions on diet and activity. Exercises can be maintain but always remember to keep your body dry and aired. Go for loose clothings and stick to the talcum powder and you would be alright. Talcum powder can also be applied to the feet to prevent tinea pedis. It is best to prevent both conditions at the same time as they are always associated with each other. During summer, if you sweat a lot, try to change your clothings more often. Changing into fresh clothings could dry up those wet area of your body. Try not to wear multiple layers of clothing, especially during summer.

If the lesion is already out and showing its signs and symptoms, you could try some topical azole antifungal compounds. Econazole or ketoconazole can be applied 2 times per day for 2 or 3 weeks. Terbinafaine can be applied once daily for 1-2 weeks. Butenafine is also very effective. Using any of the aboved mention antifungal cream should relief your symptoms fast enough. Fungal infection usually responce well to such antifungal cream. Oral antifungal agents are effective but are not indicated in uncomplicated tinea cruris. If the condition is still progressing, please consult your dermatologist as it is possible that you diagnosed yourself wrongly. The prognosis of jock itch is excellent with therapy. Remember to continue applying any of these antifungal cream even when the lesion has subside and you are feeling a lot better. It usually take few weeks to fully remove the fungi. Sticking to the 2 or 3 weeks regime will usually confirm that you are clear from the infection.

For some people, such lesion would usually trigger an allergic responce to the fungal infection. If the itch is unbearable even thou you have used the antifungal cream, try using some oral antihistamine to ease the itch. Using both of these agents at the same time is safe and proved to be quite effective in relieving symptoms.

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