Pathogenesis and pathophysiology
Also called tinea, it is an infectious mycosis of the skin, due to a fungal intrusion of the skin, hair, or nails. Common cases include hand-foot tinea, tinea corporis, tinea cruris, tinea unguium, tinea capitis and tinea versicolor. It has a high incidence rate in warm seasons and warm areas.
- Hand- foot tinea: The skin lesion is in most cases limited to the palm, sole, and between the toes. It causes itching, burning, and stinging sensations. The skin between the toes reddens, cracks open, and crumbles. In extreme long-lasting cases, the toenails may become infected, discolored, and overgrown. The fungus may spread to underside of foot, beneath the arch, producing groups of itching blisters and peeling of the skin.
- Nail tinea (onychomycosis): It results mainly from the spreading of hand-foot tinea. Its clinical manifestations include thick growth of the nail edge or the whole nail, with rough and uneven surface, loss of luster, opaqueness of the nail and the colour turning gray. The surrounding cuticle may become red, tender, and swollen, and ooze pus if a bacterial infection accompanies. It is also manifested by crispness of the affected nail, which is often incomplete or misshaped, but painless.
- Tinea corporis and Tinea cruris: Tinea on the face, neck, torso or limbs is classified as tinea corporis. Tinea cruris refers to those on the inside surface of the upper end of the thigh, including those, which spread to the genital organs or buttocks. It is manifested by ring- shaped or multi-ring-shaped erythemas with clear and prominent boundaries, papular eruptions, vesicles (lesion filled with clear fluid), scabs, which are mostly near the boundaries. The affected area may be extremely itchy.
- Tinea capitis: This is a kind of surface mycosis on the scalp and hair, found mainly among children. At first, there appear papular eruptions on the hair follicles. These are covered with grayish, or yellowish, or white scales. The scales may join together, or spread separately. The affected hair is dry and crisp, and gradually it begins scaling off unevenly. Later, the hair follicles become damaged, may result in permanent scars. The scalp itches and smells. The course is chronic.