Dermatophytosis differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Syed Hassan A. Kazmi BSc, MD [2]

Overview

Dermatophytosis should be differentiated from other superficial skin infections which may all present as a red, pruritic, annular and scaly rash on different parts of the body such as tinea versicolor, tinea nigra, white piedra, black piedra, superficial candidiasis. Tinea corporis should also be differentiated from other annular skin eruptions, especially subacute cutaneous lupus erythematosus (SCLE), granuloma annulare, and erythema annulare centrifugum.

Differential Diagnosis

Dermatophytosis should be differentiated from other superficial skin infections which may all present as a red, pruritic, annular and scaly rash on different parts of the body such as tinea versicolor, tinea nigra, white piedra, black piedra, superficial candidiasis. Tinea corporis should also be differentiated from other annular skin eruptions, especially subacute cutaneous lupus erythematosus (SCLE), granuloma annulare, and erythema annulare centrifugum.

Differential diagnoses of red, pruritic, annular, scaly rash

Name of superficial infection	Clinical presentation	Extension to hair follicle	Fungus(i)	Systemic disease	KOH preparations	Morphology in tissue sections
Tinea or ringworm	Round lesions with scaly border, accompanied by pruritis and burning	Yes; when suppurative known as kerion, when chronic known as Majocchi's granuloma	Dermatophytes (Epidermophyton spp., Trichophyton spp., Microsporum spp.)	Very rare but can invade the dermis and soft tissues, causing mycetomas	Hyphae with or without septations	Hyphae cannot be visualized in the keratin with H&E, special stains are needed
Tinea versicolor	Hypo and hyperpigmentation in patients with oily and sweaty skin, fine scales when scratching	Yes, known as Pityrosporum folliculits	Malassezia spp.	Systemic infections may occur in premature neonates receiving parenteral nutrition and in other immunosuppressed hosts	Yeasts and hyphae (“spaghetti and meat balls”)	Faintly basophilic hyphae in the stratum corneum
Tinea nigra	Brown to black macule, usually on palms, with some scaling	No	Phaeoannellomyces werneckii	Not described	Darkly pigmented, septated, and branching hyphae	Pigmented hyphae in the stratum corneum
White piedra	Creamy-white, small, soft nodules in hair shafts	No	Trichosporon spp.	Immunosuppressed patients may have lung infiltrates, renal involvement, and fungemia	Septate hyphae perpendicular to hair shaft	Not used for diagnosis
Black piedra	Hard dark nodules in hair shafts	No	Piedraia hortae	Not described	Collections of crescent ascospores surrounded by pigmented hyphae	Not used for diagnosis
Superficial candidiasis	Intertrigo, chronic paronychia, onychodystrophy, cheilitis	Yes	Candida spp.	Yes, particularly in patients with AIDS and depending on the level of immunosuppression	Yeasts, pseudohyphae may be observed	Fungal elements may be seen through the biopsy, vascular invasion must be determined

Differential diagnoses of annular skin lesions

Disease	Clinical presentation	Treatment
Tinea corporis	Scaly, annular, erythematous plaques or papules on glabrous skin	Topical and systemic antifungals
Pityriasis rosea	Small, fawn-colored, oval patches with fine scales along the borders, following skin cleavage lines	Topical and systemic corticosteroids; UVA, UVB
Granuloma annulare	Indurated, nonscaly, skin-colored annular plaques and papules, usually on the extremities	Topical and intralesional corticosteroids
Sarcoidosis	Indurated, erythematous plaques	Topical, intralesional and systemic corticosteroids; antimalarials; thalidomide
Hansen's disease	Erythematous annular plaques, with or without scale	Dapsone; rifampin (Rifadin)
Urticaria	Evanescent annular, nonscaly, erythematous plaques	Oral antihistamines
Subacute cutaneous lupus erythematosus	Annular or papulosquamous plaques, with or without scales, on sun-exposed areas	Topical, intralesional and systemic corticosteroids; antimalarials
Erythema annulare centrifugum	Annular patches with trailing scales inside erythematous borders	Topical and systemic corticosteroids; oral antihistamines; treatment of the underlying cause