Tinea

Introduction

Alias: ringworm, serpigo.

Etiology

• Trichophyton (most common)
• Microsporum
• Epidermophyton

Epidemiology

• spread by skin contact with infected persons or animals or contaminated items

Pathology

• a fungus infection (dermatophytosis) of the of the keratin component of hair, skin or nails

Clinical manifestations

• pruritus or burning sensation, or may be asymptomatic
• erythematous annular lesions growing circumferentially
  • scale surface
  • papules, vesicles or bullae may develop at advancing border
  • central clearing of annular lesions
• topical glucocorticoids may temporarily reduce inflammation & give the impression of improvement, but with rebound of symptoms with cessation of treatment
• preferentially affects warm most areas of skin

Laboratory

• microscopic examination of KOH preparations:
  • 10% KOH applied to skin scrapings or hair plucks
  • gentle heat may be applied
  • microscopic viewing for fungi
  • chlorozol black E stain
    • combines with KOH
    • stains fungus blue-black
    • contains DMSO; heating NOT necessary
  • branching hyphae seen in dermatophyte infections
  • pseudohyphae seen in candida infections
  • short fat hyphae/yeasts seen in Malassezia infection
• Wood's light (black light) on affected skin in dark room
  • yellow or green-yellow fluorescence of hair shafts suggests fungal infection
  • coral-red fluorescence is seen with erythrasma
• fungal culture
  • skin scrapings, nail clippings of hair plucks
  • Sabouraud's dextrose agar
  • Dermatophyte test medium
    • contains pH color indicator
    • dermatophyte growth increases pH of medium
    • color changes to red with increasing pH
• skin biopsy
  • rarely necessary
  • histological stain for fungi

Management

• topical antifungals
  • imidazole compounds
    • effective in treating dermatophyte, Candida & Malassezia infection
    • clotrimazole (Lotrimin)
    • miconazole (Monistat)
    • ketoconazole (Nizoral)
    • econazole (Spectazole)
    • sulconazole (Exelderm)
    • oxiconazole (Oxistat)
    • terconazole (Terazol)
  • allyamines
    • fungicidal for dermatophytes; fungistatic for Candida
    • naftifine (Naftin)
    • terbinafine (Lamisil)
    • butenafine (Lotrim Ultra)
  • cyclopirox (Loprox)
  • nystatin is effective only against Candida
• oral antifungals
  • griseofulvin
  • oral imidazoles
    • ketoconazole
    • fluconazole
    • itraconazole

More general terms

• mycosis; fungal infection

More specific terms

• Tinea barbae
• Tinea capitis
• Tinea corporis
• Tinea cruris (jock itch)
• Tinea facei
• Tinea manus
• Tinea nigra (Pityriasis nigra)
• Tinea pedis (athlete's foot)
• Tinea pseudoimbricata
• Tinea unguium
• Tinea versicolor (Pityriasis versicolor)