Description

• Superficial fungal infections of the skin/scalp; various forms of dermatophytosis; the names relate to the particular area affected (1).
  • Tinea cruris: infection of crural fold and gluteal cleft
  • Tinea corporis: infection involving the face, trunk, and/or extremities; often presents with ring-shaped lesions, hence the misnomer ringworm
  • Tinea capitis: infection of the scalp and hair; affected areas of the scalp can show characteristic black dots resulting from broken hairs.
• Dermatophytes have the ability to subsist on protein, namely keratin.
• They cause disease in keratin-rich structures such as skin, nails, and hair.
• Infections result from contact with infected persons/animals.
  • Zoophilic infections are acquired from animals.
  • Anthropophilic infections are acquired from personal contact (e.g., wrestling) or fomites.
  • Geophile infections are acquired from the soil.
• System(s) affected: skin, exocrine
• Synonym(s): jock itch; ringworm

Epidemiology

Incidence

• Tinea cruris
  • Predominant age: any age; rare in children
  • Predominant sex: male > female
• Tinea corporis
  • Predominant age: postpubertal children and young adults
  • Predominant sex: male = female
• Tinea capitis
  • Predominant age: 3 to 9 years; almost always occurs in young children
  • Predominant sex: male = female

Prevalence
Common worldwide with dramatic increase over the past 2 decades due to more frequent international travel, socioeconomic problems, and contact with animals, specifically pets

Pediatric Considerations

• Tinea cruris is rare prior to puberty.
• Tinea capitis is common in young children.

Geriatric Considerations
Tinea cruris is more common in the geriatric population due to an increase in risk factors.

Pregnancy Considerations
Tinea cruris and capitis are rare in pregnancy.

Etiology and Pathophysiology

Superficial fungal infection of skin/scalp

• Tinea cruris: Source of infection is usually the patient’s own tinea pedis, with agent being transferred from the foot to the groin via the underwear when dressing; most common causative dermatophyte is Trichophyton rubrum; rare cases are caused by Epidermophyton floccosum and Trichophyton mentagrophytes.
• Tinea corporis: most commonly caused by Trichophyton rubrum; other notable causes include Trichophyton tonsurans, Microsporum canis, T. interdigitale, Microsporum gypseum, Trichophyton violaceum, and Microsporum audouinii. It can also be caused by E. floccosum.
• Tinea capitis: T. tonsurans found in 90% and Microsporum sp. in 10% of patients. There may be a geographic predilection for certain organisms.

Genetics
Evidence suggests a genetic susceptibility in certain individuals.

Risk Factors

• Warm climates; summer months and/or copious sweating; wearing wet clothing/multiple layers (tinea cruris)
• Daycare centers/schools/confined quarters (tinea corporis and capitis)
• Depression of cell-mediated immune response (e.g., individuals with atopy or AIDS)
• Obesity (tinea cruris and corporis)
• Direct contact with an active lesion on a human, an animal, or rarely, from soil; working with animals (tinea corporis)

General Prevention

• Avoidance of risk factors, such as contact with suspicious lesions
• Fluconazole or itraconazole may be useful in wrestlers to prevent outbreaks during competitive season.

Commonly Associated Conditions

Tinea pedis, tinea barbae, tinea manus