Whorled scarring alopecia: a rare phenomenon in incontinentia pigmenti?

Incontinentia pigmenti is a rare X-linked dominant disease that affects the ectodermal tissues and is usually lethal in males. Two girls, 1 Malay and 1 Chinese, with incontinentia pigmenti of the Bloch-Sulzberger type had a whorled pattern of scarring alopecia. This phenomenon, hitherto unreported in association with this disorder, corresponded to the lines of Blaschko. The mother and maternal grandmother of the Malay girl also had whorled scarring alopecia. This phenomenon is permanent and can be used as a marker to ascertain affected adult women who may no longer have cutaneous manifestations. X chromosome inactivation in females during early embryogenesis results in a mosaic population of cells, which explains the linear and patchy cutaneous manifestations of incontinentia pigmenti.