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Tinea

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 [5] - preferentially affects warm most areas of skin Laboratory: 1) microscopic examination of KOH preparations: a) 10% KOH applied to skin scrapings or hair plucks b) gentle heat may be applied c) microscopic viewing for fungi d) chlorozol black E stain 1] combines with KOH 2] stains fungus blue-black 3] contains DMSO; heating NOT necessary e) branching hyphae seen in dermatophyte infections f) pseudohyphae seen in candida infections g) short fat hyphae/yeasts seen in Malassezia infection 2) Wood's light (black light) on affected skin in dark room a) yellow or green-yellow fluorescence of hair shafts suggests fungal infection b) coral-red fluorescence is seen with erythrasma 3) fungal culture a) skin scrapings, nail clippings of hair plucks b) Sabouraud's dextrose agar c) Dermatophyte test medium 1] contains pH color indicator 2] dermatophyte growth increases pH of medium 3] color changes to red with increasing pH 4) skin biopsy a) rarely necessary b) histological stain for fungi Management: 1) topical antifungals a) imidazole compounds - effective in treating dermatophyte, Candida & Malassezia infection - clotrimazole (Lotrimin) - miconazole (Monistat) - ketoconazole (Nizoral) - econazole (Spectazole) - sulconazole (Exelderm) - oxiconazole (Oxistat) - terconazole (Terazol) b) allyamines - fungicidal for dermatophytes; fungistatic for Candida - naftifine (Naftin) - terbinafine (Lamisil) - butenafine (Lotrim Ultra) c) cyclopirox (Loprox) d) nystatin is effective only against Candida 2) oral antifungals a) griseofulvin b) oral imidazoles - ketoconazole - fluconazole - itraconazole

Specific

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)

General

mycosis; fungal infection

References

  1. Stedman's Medical Dictionary 26th ed, Williams & Wilkins, Baltimore, 1995
  2. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996
  3. Prescriber's Letter 16(8): 2009 Topical Treatment of Superficial Fungal Infections Detail-Document#: 250806 (subscription needed) http://www.prescribersletter.com
  4. Gupta AK, Chaudhry M, Elewski B. Tinea corporis, tinea cruris, tinea nigra, and piedra. Dermatol Clin. 2003 Jul;21(3):395-400, v. PMID: 12956194
  5. Medical Knowledge Self Assessment Program (MKSAP) 16, 18. American College of Physicians, Philadelphia 2012, 2018.
  6. Prescriber's Letter 21(5): 2014 Topical Antifungal Agents for Tinea Infections Detail-Document#: 300507 (subscription needed) http://www.prescribersletter.com
  7. Moriarty B, Hay R, Morris-Jones R. The diagnosis and management of tinea. BMJ. 2012 Jul 10;345:e4380 PMID: 22782730