Tinea Capitis
Most cases of tinea capltls occur in children, but adult infections, especially with Trichophyton tonsurans, are occasionally seen. One or more sharply marginated, localized patches of complete alopecia are characteristically present in tinea capitis. This hair loss is characterized by the fact that the hairs are broken off at, or close to, the surface of the skin. This results in the presence of fine stubble that, if too short to palpate, is sometimes visible as a series of black dots within the patch of alopecia. A sharply marginated, red, scaling plaque is present on the scalp, its location matches precisely with the area of alopecia. The severity of the inflammation varies with the type of fungus responsible for the infection.
Infections resulting from Microsporum audouini and tonsurans may be relatively noninflammatory and therefore somewhat inapparent, whereas those resulting from Miaosporum canis and Trichophyton mentagro Phytes are usually bright red and edematous. Marked inflammatory changes, known as kerion formation, may be accompanied by pustulation around some of the follicles. Only the Miaosporum sp. infections fluoresce under Wood’s lamp illumination. Confirmation of suspected tinea capitis can be obtained with the use of potassium hydroxide (KOH) preparations and fungal cultures. Treatment of tinea capitis always requires orally administered griseofulvin; topically applied antifungal agents are insufficient. Steroids may be necessary in cases of severe kerion formation. Successful treatment of tinea capitis is almost always accompanied by complete regrowth of hair.
Lupus Erythematosus
Localized patterns of hair loss regularly develop when lesions of discoid lupus erythematosus occur in the scalp. Here, too, the area of hair loss is very sharply localized. Since the skin in the center of such lesions may be hypopigmented, however, the presence of actual scalp disease may at first go unrecognized.
Erythematous border that is distinctive
for the diseases. The scalp lesions of discoid lupus erythematosus rarely occur alone. The presence of typical facial lesions helps to suggest the correct diagnosis. Hair loss occasionally occurs in systemic lupus erythematosus, but it is more diffuse and is often not associated with visible scalp disease.
Seborrheic Dennatitis and Psoriasis
Some patients with inflammatory dandruff (seborrheic dermatitis) or widespread psoriasis of the scalp complain of diffuse hair loss. Such loss may be real, although it is probably only exaggerated normal telogen loss and in any event is seldom apparent to the examiner. When present, it occurs from large portions of the scalp and thus lacks the patchiness found in tinea capitis and discoid lupus erythematosus. The underlying scalp disease is that of an inflammatory, scaling process. The amount of scale varies with the frequency and vigor with which the patient shampoos. Seborrheic dermatitis of the scalp severe enough to result in hair loss is generally accompanied by seborrheic dermatitis of the retroauricular and nasal folds. Alopecia associated with seborrheic dermatitis or psoriasis may be continuous, but it is not progressive. Therefore, visible baldness should not be ascribed to either disease. A vicious circle often occurs in which patients experience most of their hair loss during shampooing and thus decrease the frequency with which they wash their hair. This, in turn, is followed by worsening of the underlying disease and accumulation of loose telogen hairs, which are then shed when the scalp is once again finally shampooed. Hair regrowth occurs normally when seborrheic dermatitis or psoriasis is adequately treated.