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Fungal Overview

PATIENT STORY

A 55-year-old woman presents with a red pruritic area on her face for 3 months (Figure 141-1). The annular distribution immediately is suspicious for a dermatophyte infection. Further investigation demonstrates that the patient has severe tinea pedis in a moccasin distribution. The patient is treated with an oral terbinafine 250 mg daily for 1 month and her fungal infection clears completely.

FIGURE 141-1

Tinea faciei on the face of a 55-year-old woman with typical scaling and ringlike pattern (ringworm). Note the well-demarcated raised border and central clearing. (Reproduced with permission from Richard P. Usatine, MD.)

INTRODUCTION

Fungal infections of the skin and mucous membranes are ubiquitous and common. There are many types of fungus that grow on humans, but they all share a predilection for warm and moist areas. Consequently, hot and humid climates promote fungal infections, but many areas of the skin can get warm and sweaty even in cold climates, such as the feet and groin.

SYNONYMS

Pityriasis versicolor equals tinea versicolor.

PATHOPHYSIOLOGY

Mucocutaneous fungal infections are caused by:

  • Dermatophytes in three genera: Microsporum, Epidermophyton, and Trichophyton. There are approximately 40 species in the three genera, and these fungi cause tinea pedis and manus, tinea capitis, tinea corporis, tinea cruris, tinea faciei, and onychomycosis (Figures 141-1, 141-2, 141-3, 141-4, 141-5, 141-6).

  • Yeasts in the genera of Candida and Pityrosporum (Malassezia)—There are also multiple types of Candida species. Pityrosporum is the cause of seborrhea and tinea versicolor (Figures 141-7 and 141-8). Although tinea versicolor has the name tinea in it, it is not a true dermatophyte and may be best called pityriasis versicolor.

FIGURE 141-2

Annular pruritic lesion with concentric rings in the axilla of a young woman caused by tinea corporis. The concentric rings have a high specificity for tinea infections. (Reproduced with permission from Richard P. Usatine, MD.)

FIGURE 141-3

Tinea cruris with well-demarcated raised border and no central clearing. (Reproduced with permission from Richard P. Usatine, MD.)

FIGURE 141-4

Tinea corporis on the right flank of a woman bending forward. Note that post-inflammatory hyperpigmentation is seen in the skin affected by the tinea corporis. (Reproduced with permission from Richard P. Usatine, MD.)

FIGURE 141-5

Tinea capitis in a 5-year-old black girl with hair loss and an inflammatory response. Her kerion is healing ...

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