Pityriasis amiantacea is a chronic disease that occurs on the scalp and is characterized by diffuse, accumulated, amianthoid scales, mostly in children and young adults, more common in females, with protracted duration.


Causes

The etiology and pathogenesis of pityriasis amiantacea are unknown. According to keratodermia at the follicular orifices and scaly hair sheaths around the hairs in the skin lesions, it is thought that the disease may be associated with follicular keratosis. It is also believed that the disease is a special reaction to scalp trauma or infections. In addition, the disease can also be secondary to psoriasis, seborrheic dermatitis, and streptococcal infection.


Signs and Symptoms

There are large amounts of grayish white, dry, amianthoid, scaly scabs on the scalp, resembling amianthus. In severe cases, most area of the scalp can be involved. Scales and scabs are attached accumulatively to the hairs, so that there are clustered hairs. Hairs are not invaded, but there may be mild flushing on the scalp under the scales or temporary hair loss. There are not obvious inflammation and subjective symptoms. Occasionally, mild pruritus may be present.

Figure 1 pityriasis amiantacea


Diagnosis

On the basis of large amounts of grayish white, amianthoid scales on the scalp, unaffected hairs, and chronic development, the disease can be diagnosed.


Treatment

The treatment regimen is shampooing with selenium sulfide lotion, 2% ketoconazole lotion, or compound ketoconazole lotion 2 - 3 times a week for 2 - 4 weeks. Topical compound sulfur ointment, 10% sulfur cream, econazole cream, or compound econazole nitrate cream twice a day can also be applied.