Tinea Corporis Bolognia

Tinea corporis Tinea corporis is a dermatophyte infection of the skin of the trunk and extremities excluding the hair, nails, palms, soles and groin. The infection is generally restricted to the stratum corneum and most commonly occurs on exposed skin, but it can develop on any part of the body. While tinea corporis is seen worldwide, it is most common in tropical regions. Any dermatophyte can potentially cause tinea corporis, but T. rubrum is the most common pathogen worldwide, followed by T. mentagrophytes (Table 76.7).

Table 76.7 --Common dermatophytes that cause tinea corporis. COMMON DERMATOPHYTES THAT CAUSE TINEA CORPORIS

DermatophyteClinical features

Anthropophilic

Trichophyton rubrumCommonly harbored by hair follicles; may produce concentric rings; can recur; causative organism in Majocchi's granuloma and most common cause of tinea corporis

T. tonsuransCommonly seen in adults who care for children with tinea capitis caused by this organism

Epidermophyton floccosumGenerally restricted to groin, feet; responsible for eczema marginatum

T. concentricumResponsible for tinea imbricata; infections typically chronic

T. mentagrophytes var. interdigitaleCauses interdigital tinea pedis, tinea cruris and onychomycosis

Zoophilic

T. mentagrophytes var. mentagrophytesMay be associated with dermatophytid reaction; causes inflammatory tinea pedis and tinea barbae; associated with exposure to small mammals

Microsporum canisAssociated with pet exposure (cat or dog)

T. verrucosumMay mimic bacterial furunculosis; associated with exposure to cattle

Geophilic

M. gypseumFrequently associated with outdoor/occupational exposure; lesions may be inflammatory or bullous

Tinea corporis can result from human-to-human, animal-to-human or soil-to-human spread (see Table 76.6). Domestic animals are an important factor in the transmission of organisms causing tinea corporis, specifically the zoophilic species. Another important risk factor in acquiring tinea corporis is having a personal history of, or close contact with, tinea capitis or tinea pedis. Other factors that may predispose an individual to tinea corporis include occupational or recreational exposure (e.g. military housing, gymnasiums, locker rooms, outdoor occupations, wrestling), contact with contaminated clothing and furniture, and immunosuppression[13].There are various clinical presentations of tinea corporis, and they can mimic other dermatologic conditions (Table 76.8). As with most dermatophyte infections, the extent of inflammation depends on the causative pathogen and the immune response of the host. Also, because hair follicles serve as reservoirs for infection, areas of the body with more hair follicles may display a more pronounced inflammatory response.

Table 76.8 --Differential diagnoses of dermatophyte infections. DIFFERENTIAL DIAGNOSES OF DERMATOPHYTE INFECTIONS

Tinea corporisTinea crurisTinea facieiTinea capitisTinea pedis

Dermatitis

Nummular eczema

Atopic

Stasis

Contact

Seborrheic (petaloid)

Pityriasis versicolor

Pityriasis rosea

Parapsoriasis

Erythema annulare centrifugum

Annular psoriasis

Subacute lupus erythematosus

Granuloma annulare

Impetigo

Cutaneous candidiasis

Intertrigo

Seborrheic dermatitis

Psoriasis

Erythrasma

Contact dermatitis

Lichen simplex chronicus

Parapsoriasis/mycosis fungoides

HaileyHailey disease

Langerhans cell histiocytosis

Dermatitis

Seborrheic

Perioral

Contact

Acne rosacea

Lupus erythematosus

Acne vulgaris

Annular psoriasis (children)

Seborrheic dermatitis

Alopecia areata

Trichotillomania

Psoriasis

If pustules:

Pyoderma

Folliculitis

If scarring:

Lichen planus

Discoid lupus erythematosus

Folliculitis decalvans

Central centrifugal cicatricial alopecia

Dermatitis

Dyshidrotic

Contact

Psoriasis

Vulgaris

Pustular

Juvenile plantar dermatosis

Secondary syphilis

If interdigital:

Erythrasma

Bacterial infection, e.g. GNR

GNR, Gram-negative rods.

The typical incubation period is 1 to 3 weeks. Infection spreads centrifugally from the point of skin invasion, with central clearing of the fungus, typically resulting in annular lesions of varying sizes (Fig. 76.4A). However, lesions may assume other shapes (e.g. arcuate, circinate, oval) (Fig. 76.4B). Most are scaly, although scale may be lessened or absent if topical corticosteroids have been used (tinea incognito). Pustules within the active border is a finding suggestive of tinea

Fig. 76.4 Tinea corporis. A Annular lesion on the arm with active scaly border. B Widespread involvement of the back with scalloped inferior border. C Pustules within multiple figurate lesions on the upper arm.

Clinical variants of tinea corporis include tinea profunda, Majocchi's granuloma and tinea imbricata. Tinea profunda results from an excessive inflammatory response to a dermatophyte (analogous to a kerion on the scalp). It may have a granulomatous or verrucous appearance and be mistaken for cutaneous tuberculosis, a dimorphic fungal infection or squamous cell carcinoma. Majocchi's granuloma, caused by T. rubrum, is characterized by perifollicular pustules or granulomas (Fig. 76.5). This variant, commonly seen in women who have tinea pedis or onychomycosis (caused by T. rubrum) and who also shave their legs, occurs when infected hairs penetrate the wall of the follicle. The lesions may be extensive and possibly vegetating, and also occur in the setting of immunosuppression.

Fig. 76.5 Majocchi's granuloma. Perifollicular inflammation and pustules on the buttocks due to Trichophyton rubrum.