Poliosis (whitening of the hair) may occur as a generalized or local change. The latter is termed poliosis circumscripta.
The white forelock is an example of poliosis circumscripta involving the scalp.
Conditions associated with poliosis circumscripta:
(1) familial occurrence of a forelock
(2) adjacent to a melanocytic lesion (nevus, blue nevus, malignant melanoma)
(3) adjacent to a neurofibroma
(4) associated with tuberous sclerosis
(5) localized inflammation
(6) piebaldism
If a patient shows poliosis circumscripta then it is important to examine the area for signs of an adjacent tumor.
