INCONTINENTIA pigmenti is a peculiar skin disease, probably developmental in origin, characterized by an extremely striking and bizarre arrangement of pigmented macules in polyangular flecks, whorls, spidery forms, lines, and patches. These chocolate-brown designs do not follow lines of cleavage or distributions of nerves, nor do they respect the limitations of the midline. Areas of alopecia in the scalp appear frequently, and many other ectodermal and mesodermal defects occur, although they are less well known. One feature of this odd cutaneous anomaly has only been touched on in the literature, and yet it is perhaps the most peculiar aspect of the disease: the pigmentary anomaly is frequently heralded by inflammatory lesions, particularly bullae, in lines and patches. The bullae disappear and recur for weeks or months and then finally give way, either to the pigmented macules directly or to an intermediate temporary stage of linear verrucous lesions which gradually fade