AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

Tinea cruris, a pruritic superficial fungal infection of the groin and adjacent skin, is the second most common clinical presentation for dermatophytosis. Tinea cruris is a common and important clinical problem that may, at times, be a diagnostic and therapeutic challenge.

The following other eMedicine articles on tinea infections may be of interest:

• Tinea Barbae
• Tinea Capitis
• Tinea Corporis
• Tinea Faciei
• Tinea Nigra
• Tinea Pedis
• Tinea Versicolor

Pathophysiology

The most common etiologic agents for tinea cruris include Trichophyton rubrum and Epidermophyton floccosum; less commonly Trichophyton mentagrophytes and Trichophyton verrucosum are involved. Tinea cruris is a contagious infection transmitted by fomites, such as contaminated towels or hotel bedroom sheets, or by autoinoculation from a reservoir on the hands or feet (tinea manuum, tinea pedis, tinea unguium). The etiologic agents produce keratinases, which allow invasion of the cornified cell layer of the epidermis. The host immune response may prevent deeper invasion. Risk factors for initial infection or reinfection include wearing tight-fitting or wet clothing or undergarments.

Frequency

United States

Dermatophytosis accounts for approximately 10-20% of all visits to dermatologists.

International

Tinea cruris has a worldwide distribution but is found more commonly in hot humid climates.

Mortality/Morbidity

No mortality is associated with tinea cruris. Associated pruritus leads to morbidity resulting from lichenification, secondary bacterial infection, and irritant and allergic contact dermatitis caused by topically applied medications.

Sex

Tinea cruris is 3 times more common in men than in women.

Age

Adults are affected much more commonly than are children.

CLINICAL

Section 3 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

History

Patients complain of pruritus and rash in the groin. A history of previous episodes of a similar problem usually is elicited. Additional historical information may include recently visiting a tropical climate, wearing tight-fitting clothes (including bathing suits) for extended periods, sharing clothing with others, participating in sports, or coexisting diabetes mellitus or obesity. Prison inmates, members of the armed forces, members of athletic teams, and people who wear tight clothing may be subject to independent or additional risk for dermatophytosis.

Physical

Tinea cruris manifests as a symmetric erythematous rash in the groin.

• Large patches of erythema with central clearing are centered on the inguinal creases and extend distally down the medial aspects of the thighs and proximally to the lower abdomen and pubic area.
• Scale is demarcated sharply at the periphery.
• In acute infections, the rash may be moist and exudative.
• Chronic infections typically are dry with a papular annular or arciform border and barely perceptible scale at the margin.
• Central areas typically are hyperpigmented and contain a scattering of erythematous papules and a little scale.
• The penis and scrotum typically are spared; however, the infection may extend to the perineum and buttocks.
• Secondary changes of excoriation, lichenification, and impetiginization may be present as a result of pruritus.
• Chronic infections modified by the application of topical corticosteroids are more erythematous, less scaly, and may have follicular pustules.
• Approximately one half of patients with tinea cruris have coexisting tinea pedis.
• Erythematous-scale plaques and erythematous-liquenificated plaques were the most frequently found clinical types in an excellent Brazilian study.¹ T rubrum was the prevalent dermatophyte in 90% of the cases, followed by T tonsurans (6%) and T mentagrophytes (4%).

Causes

The dermatophyte T rubrum is the most common etiologic agent for tinea cruris. In a Brazilian series, T rubrum was the prevalent dermatophyte in 90% of the cases, followed by T tonsurans (6%) and T mentagrophytes (4%).¹ Other organisms, including E floccosum and T verrucosum, cause an identical clinical condition. T rubrum and E floccosum infections are more apt to become chronic and noninflammatory, while infection by T mentagrophytes often is associated with an acute inflammatory clinical presentation.

DIFFERENTIALS

Section 4 of 11  

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• Clinical
• Differentials
• Workup
• Treatment
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• Follow-up
• Miscellaneous
• Multimedia
• References

Other Problems to be Considered

Histiocytosis X
Psoriasis inversus

WORKUP

Section 5 of 11  

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• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• Microscopic examination of a potassium hydroxide (KOH) wet mount of scales is diagnostic. The procedure for KOH wet mount is as follows:
• • Clean the area with 70% alcohol.
  • Collect scales from the margin of the lesion; use a scalpel or the edge of a glass slide for this purpose. Cover the collected scales with a cover slip; allow a drop of KOH (10-15% wt/vol) to run under the cover slip.
  • The keratin and debris should dissolve after a few minutes. The process can be hastened by heating the slide or by the addition of a keratolytic or dimethyl sulfoxide to the KOH formulation.
  • The addition of 1 drop of lactophenol cotton blue solution to the wet mount preparation heightens the contrast and aids in the diagnosis.
  • Negative results on KOH preparation do not exclude fungal infection.
  • Scale culture is useful for fungal identification but is a more specific, albeit less sensitive, diagnostic test than KOH wet mount.
• Growth on Mycosel or Sabouraud agar plates usually is sufficient within 3-6 weeks to allow specific fungal identification.

Procedures

• Negative KOH wet mount examination and cultures exclude other conditions in the differential diagnosis. If tinea cruris still is suggested, repeat the tests, several times if necessary.
• Punch biopsy is diagnostic but has low sensitivity and low specificity. Using periodic acid-Schiff stain (fungal elements appear pink) or methenamine silver stains (fungal elements appear brown or black) on the processed tissue enhances the sensitivity of the biopsy procedure.
• Wood lamp examination may be helpful to exclude erythrasma, which reveals coral red florescence of the affected area.

Histologic Findings

Microscopic examination of hematoxylin and eosin–stained tissue sections reveals patterns of inflammation strongly suggestive of dermatophyte infection. The inflammation typically is perivascular; the epidermis exhibits spongiosis or a psoriasiform pattern of hyperplasia. Granulomatous dermatitis may accompany folliculitis.

Specific diagnostic findings include the presence of neutrophils in the cornified cell layer and the sandwich sign, in which fungal elements are sandwiched between 2 zones of differing structure within the cornified cell layer. The upper zone of the cornified cell layer has a typical basket-weave pattern of orthokeratosis, while the lower zone consists of more compact orthokeratosis and parakeratosis. The presence of spores and branching hyphae can be confirmed using periodic acid-Schiff or methenamine silver stains, but histologic examination provides no clues regarding the dermatophyte species.

TREATMENT

Section 6 of 11  

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• Differentials
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• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical Care

Clinical cure of an uncomplicated infection usually can be achieved using topical antifungal agents of the imidazole or allylamine family. Consider patients unable to use topical treatments consistently or with extensive or recalcitrant infection as candidates for systemic administration of antifungal therapy.

Prevention of reinfection is an essential component of disease management. Patients with tinea cruris often have concurrent dermatophyte infections of the feet and hands.

• Treat all active areas of infection simultaneously to prevent reinfection of the groin from other body sites.
• Advise patients with tinea pedis to put on their socks before their undershorts to reduce the possibility of direct contamination.
• Advise patients with tinea cruris to dry the crural folds completely after bathing and to use separate towels for drying the groin and other parts of the body.

Diet

Recommend weight loss for patients who are obese and have tinea cruris.

MEDICATION

Section 7 of 11  

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• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

To achieve the best results, particularly with follicular or extensive disease, the authors often recommend a combination of topical and systemic therapy.

Drug Category: Antifungal agents

The 2 classes of antifungal medications used most commonly to treat tinea cruris are the azoles and the allylamines. Azoles inhibit the enzyme lanosterol 14-alpha-demethylase, an enzyme that converts lanosterol to ergosterol, which is an important component of the fungal cell wall. Membrane damage results in permeability problems and renders the fungus unable to reproduce. Allylamines inhibit squalene epoxidase, which is an enzyme that converts squalene to ergosterol, resulting in the accumulation of toxic levels of squalene in the cell and in cell death. Examples of both classes of antifungal agents are available for topical and systemic administration.

FOLLOW-UP

Section 8 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Further Outpatient Care

• Repeat scraping or culture may be indicated if treatment is unsuccessful.

Deterrence/Prevention

• Recurrence of the disease is common; therefore, it is of utmost importance to treat concurrent fungal infections and to keep the groin region dry to prevent recurrence of tinea cruris. Advise patients to dry the area after bathing, using a towel or a hair dryer.
• Advise patients to avoid wearing tight-fitting clothing to prevent moisture build-up.
• Advise patients who are obese to lose weight.
• Advise patients to put on socks before undergarments to minimize the possibility of fungal transfer from the feet to the groin.
• Antifungal powders, which have the added benefit of drying the region, may be helpful in preventing recurrence.

Complications

• Tinea cruris can become infected secondarily by candidal or bacterial organisms. In addition, the area can become lichenified and hyperpigmented in the setting of a chronic fungal infection.
• Mistreatment of tinea cruris with topical steroids can result in exacerbation of the disease. Although patients may note initial relief of symptoms, the infection may spread.

Prognosis

• The prognosis of tinea cruris is excellent with appropriate diagnosis and treatment; however, recurrence is likely if the groin region is not kept dry.

Patient Education

• Educate patients about the risks of sharing sheets and undergarments with others and about the need to keep the groin region dry (see Deterrence/Prevention).
• For excellent patient education resources, visit eMedicine's Skin, Hair, and Nails Center. Also, see eMedicine's patient education article Ringworm on Body.

MISCELLANEOUS

Section 9 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• Failure to check a patient's medication list for possible drug interactions
• Failure to monitor blood work, which may be necessary with administration of oral antifungals

MULTIMEDIA

Section 10 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  Tinea cruris.
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Media file 2:  Tinea cruris.
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Media file 3:  Tinea cruris.
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Media file 4:  Tinea cruris (hematoxylin and eosin stain).
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Media file 5:  Tinea cruris (periodic acid-Schiff stain, magnification X 20).
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Media file 6:  Tinea cruris (Gomori methenamine-silver stain, magnification X 20).
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Media type:  Photo

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

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Article Last Updated: May 20, 2008