Tinea cruris
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Tinea cruris (TC), also known as jock itch, is a common type of contagious, superficial fungal infection of the groin and buttocks region, which occurs predominantly but not exclusively in men and in hot-humid climates.<ref name="Lehrer2019">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="EdwardsLynch2010">Template:Cite book</ref>
Typically, over the upper inner thighs, there is an intensely itchy red raised rash with a scaly well-defined curved border.<ref name="Lehrer2019"/><ref name="EdwardsLynch2010"/> It is often associated with athlete's foot and fungal nail infections, excessive sweating, and sharing of infected towels or sports clothing.<ref name="EdwardsLynch2010"/><ref name="Rook2016"/><ref name=Nadalo2006/> It is uncommon in children.<ref name="EdwardsLynch2010"/>
Its appearance may be similar to some other rashes that occur in skin folds including candidal intertrigo, erythrasma, inverse psoriasis and seborrhoeic dermatitis. Tests may include microscopy and culture of skin scrapings.<ref name=DermnetNZ2003/>
Treatment is with topical antifungal medications and is particularly effective if symptoms have recent onset.<ref name="Rook2016"/><ref name=Nadalo2006/> Prevention of recurrences include treating concurrent fungal infections and taking measures to avoid moisture build-up including keeping the groin region dry, avoiding tight clothing and losing weight if obese.<ref name=Wiederkehr2020/>
NamesEdit
Other names include "jock rot",<ref name="Bedson2005">Template:Cite book</ref> "dhobi itch",<ref name="Partridge2006">Template:Cite book</ref> "crotch itch",<ref name="RosenthalWilliams2006">Template:Cite book</ref> "scrot rot",<ref name="Jessen2010">Template:Cite book</ref> "gym itch", "ringworm of groin" and "eczema marginatum".<ref name="NucciOliva2019">Template:Cite book</ref>
Signs and symptomsEdit
Typically, over the upper inner thighs, there is a red raised rash with a scaly well-defined border. There may be some blistering and weeping, and the rash can reach near to the anus.<ref name="Lehrer2019"/> The distribution is usually on both sides of the groin and the center may be lighter in colour.<ref name=Wiederkehr2020/> The rash may appear reddish, tan, or brown, with flaking, rippling, peeling, iridescence, or cracking skin.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
If the person is hairy, hair follicles can become inflamed resulting in some bumps (papules, nodules and pustules) within the plaque. The plaque may reach the scrotum in men and the labia majora and mons pubis in women. The penis is usually unaffected unless there is immunodeficiency or there has been use of steroids.<ref name="EdwardsLynch2010"/>
Affected people usually experience intense itching in the groin which can extend to the anus.<ref name="Lehrer2019"/><ref name="EdwardsLynch2010"/>
CausesEdit
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Tinea cruris is often associated with athlete's foot and fungal nail infections.<ref name="EdwardsLynch2010"/><ref name="Rook2016">Template:Cite book</ref> Rubbing from clothing, excessive sweating, diabetes and obesity are risk factors.<ref name=Nadalo2006>Template:Cite journal</ref><ref name="Wiederkehr2020"/> It is contagious and can be transmitted person-to-person by skin-to-skin contact or by contact with contaminated sports clothing and sharing towels.<ref name="Lehrer2019"/><ref name="Rook2016"/>
The type of fungus involved may vary in different parts of the world; for example, Trichophyton rubrum and Epidermophyton floccosum are common in New Zealand.<ref name=DermnetNZ2003/> Less commonly Trichophyton mentagrophytes and Trichophyton verrucosum are involved.<ref name="Wiederkehr2020"/> Trichophyton interdigitale has also been implicated.<ref name="Rook2016"/>
DiagnosisEdit
Tests are usually not needed to make a diagnosis, but if required, may include microscopy and culture of skin scrapings, a KOH examination to check for fungus, or skin biopsy.<ref name="Lehrer2019"/><ref name=DermnetNZ2003/>
Differential diagnosisEdit
The symptoms of tinea cruris may be similar to other causes of itch in the groin.<ref name="Lehrer2019"/> Its appearance may be similar to some other rashes that occur in skin folds including candidal intertrigo, erythrasma, inverse psoriasis and seborrhoeic dermatitis.<ref name=DermnetNZ2003>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
PreventionEdit
To prevent recurrences of tinea cruris, concurrent fungal infections such as athlete's foot need to be treated. Also advised are measures to avoid moisture build-up including keeping the groin region dry, avoiding tight clothing, and losing weight if obese.<ref name="Wiederkehr2020">Template:Cite journal</ref> People with athlete's foot or tinea cruris can prevent spread by not lending their towels to others.<ref name="Rook2016"/>
TreatmentEdit
Tinea cruris is treated by applying antifungal medications of the allylamine or azole type to the groin region. Studies suggest that allylamines (naftifine and terbinafine) are a quicker but more expensive form of treatment compared to azoles (clotrimazole, econazole, ketoconazole, oxiconazole, miconazole, sulconazole).<ref name=Nadalo2006/> If the symptoms have been present for long or the condition worsens despite applying creams, terbinafine or itraconazole can be given by mouth.<ref name="Rook2016"/>
The benefits of the use of topical steroids in addition to an antifungal are unclear.<ref name="EL2014">Template:Cite journal</ref> There might be a greater cure rate but no guidelines currently recommend its addition.<ref name=EL2014/> The effect of Whitfield's ointment is also unclear,<ref name=EL2014/> but when given, it is prescribed at half strength.<ref name="Rook2016"/>
Wearing cotton underwear and socks, in addition to keeping the groin dry and using antifungal powders, is helpful.<ref name="CrainGershel2010">Template:Cite book</ref>
PrognosisEdit
Tinea cruris is not life-threatening and treatment is effective, particularly if the symptoms have not been present for long.<ref name="Rook2016"/> However, recurrence may occur. The intense itch may lead to lichenification and secondary bacterial infection. Irritant and allergic contact dermatitis may be caused by applied medications.<ref name="Wiederkehr2020"/>
EpidemiologyEdit
Tinea cruris is common in hot-humid climates, and is the second most common clinical presentation for dermatophytosis.<ref name="Wiederkehr2020"/> It is uncommon in children.<ref name="EdwardsLynch2010"/>
ReferencesEdit
External linksEdit
Template:Medical resources Template:Diseases of the skin and appendages by morphology Template:Mycoses