Dermatophytosis

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Contents 1 More Specific Terms 2 Introduction 3 Etiology 4 Epidemiology 5 Pathology 6 Clinical-manifestations 7 Laboratory 8 Differential-diagnosis 9 Management 10 More General Terms 11 Additional Terms 12 References

More Specific Terms

• onychomycosis
• Tinea

Introduction

• Superficial fungus infection of the skin, hair &/or nails (keratinized tissue) including:
• Tinea: Tinea facialis, Tinea corporis, Tinea cruris, Tinea pedis, Tinea capitis, Tinea barbae
• dermatophytic folliculitis
• Majocchi's granuloma
• onychomycosis

Etiology

• Dermatophytes (more than 40 species recognized)

• Epidermophyton
• Microsporum
• Trichophyton

• immunosuppression is a predisposing factor

Epidemiology

• person to person or animal to person spread by fomites
• contact with contaminated soil (less common)

Pathology

• organisms invade the stratum corneum, hair & nails
• inflammation of the underlying layers of skin occurs
• the degree of inflammation depends upon the host response to the organism

• geophilic organisms produce the greatest response
• anthrophilic organisms induce less inflammation

• cell-mediated immunity & antimicrobial activity of polymorphonuclear leukocytes restrict dermatophyte pathogenicity

Clinical-manifestations

• inflammation in the epidermis & upper dermis resembles eczema
• distinguishing feature is sharp, scaly borders with central clearing

Laboratory

• microscopic examination of a scale from the border of an active lesion using 10% KOH shows septate hyphae
• culture of skin scraping on fungal media

• Sabouraud's dextrose agar
• dermatophyte test medium

• collect using #15 blade scalpel or edge of microscope slide
• fungi best demonstrated with PAS or methenamine silver

Differential-diagnosis

• cutaneous candidiasis [3]

• microscopic exam with KOH shows budding yeast or short non septate hyphae
• cutaneous candidiasis of the scrotum is common, Tinea infections of the scrotum are rare
• satellite lesions are classic for cutaneous candidiasis

• Tinea versicolor also shows short hyphae & yeast forms [3]

Management

• topical antifungal agents ( over the counter):

• miconazole
• clotrimazole
• terbonafine
• avoid topical glucocorticoids [3]

• systemic agents

• indications:

• tinea capitis & tinea unguium (onychomysosis)
• extensive tinea corporis
• topical treatment-resistant dermatophytosis

• systemic antifungals

• terbinafine
• itraconazole
• ketoconazole
• griseofulvin

• see specific agents

More General Terms

• mycosis; fungal infection
• skin disease (dermatologic disorder, dermatopathy, dermatosis)

Additional Terms

• clotrimazole (Lotrimin, Mycelex, Gyne-Lotrimin)
• Dermatophyte
• fomite
• griseofulvin (Fulvicin, Grifulvin, Grisactin)
• itraconazole (Sporanox)
• ketoconazole (Nizoral, Xolegel)
• miconazole (Monistat, Lotrimin AF)
• terbinafine (Lamisil)

References

1. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 919
2. Color Atlas & Synopsis of Clinical Dermatology, Common & Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY, 1997, pg 688-691
3. Medical Knowledge Self Assessment Program (MKSAP) 14, 15 American College of Physicians, Philadelphia 2006, 2009

dermatophytosis