Pseudocyst of the scalp.

We describe 4 cases of pseudocyst of the scalp, which still is only being described in the Japanese literature. The tumor is characterized as follows: localized between the top and the forehead area of the scalp, it first appears as a solitary reddish, painful small nodule or papule; it then gradually increases in size, protruding into a dome-shaped mass, and becomes associated with alopecia limited to the lesion area. This report describes typical cases of pseudocyst of the scalp, reviews the reported Japanese cases and introduces this tumor to western dermatology.