fungal skin infections

Dermatology Dr. Hussein A. Al-Sultany
2015-2016

Fungal Skin Infections

Microbiology: Fungi exist in two basic forms:
1- Molds (consist of long filaments of cells called hyphae) as Dermatophyte, the molds grow and fragment into spores.
2- Yeasts (single cell) as Candida, which is reproduced by budding.
Some fungi are dimorphic (can exist as yeast or mold depending on the temperature) as Pityrosporum.

Dermatophyte Infections
? Dermatophytes, have the ability to infect and survive on keratin only (skin, hair, and nail).
? They caused by three genera: Microsporum, Trichophyton, and Epidermophyton.
? Dermatopyte classified according to their origin into: Anthropophilic (human source), Zoophilic (animal source), Geophilic (soil source).
Zoophilic infections usually elicit a brisk inflammatory response.

Clinical presentation:
Infections with dermatophytes are usually called Tinea (ringworm); for further description, the anatomical site is added, including:

1- Tinea of the trunk and limbs (Tinea corporis or T. circinata):
It can occur at any age. The clinical infection usually starts from an inoculation site and spreads peripherally, where the lesion becomes more pronounced (active border).
The active border: is a very characteristic pattern of dermatophyte infection, typically the active border is scaly, red, and slightly elevated, a few small vesicles and pustules may be seen within them. The lesions expand slowly and healing in the centre leaves a typical ring-like pattern, this characteristic annular appearance results from the immunological elimination of the fungus from the centre of the lesion, and the subsequent resolution of the inflammatory host response at that site.

2- Tinea of the groin (Tinea cruris):
This is common and affects men more often than women. The children are rarely affected. The upper inner thigh is involved and lesions expand slowly to form sharply demarcated plaques with active border. The scrotum is usually spared.
DDX: intertrigo, contact dermatitis (irritant or allergic), candidiasis, erythrasma (bacterial infection), psoriasis, and seborrhoeic dermatitis.

3- Tinea of the face (Tinea faciei):
It is limited to the glabrous skin of the face in adult males. In pediatric and female patients, the infection may appear on any surface of the face, including the upper lip and chin.
The lesions have annular shape with active border

4- Tinea of the beard (Tinea barbae):
It is a superficial dermatophyte infection that is limited to the beard areas of the face and neck and occurs almost exclusively in adult males.
Like tinea capitis, the hairs are infected and easily removed (easily epilation).