Analysis of 54 cases of hypopigmentation and hyperpigmentation along the lines of Blaschko.

OBJECTIVE: To define the spectrum of disease in cases of hypopigmentation and hyperpigmentation along the lines of Blaschko more accurately. Pigmentary anomalies along the lines of Blaschko, including hypomelanosis of Ito, linear and whorled nevoid hypermelanosis, and nevus depigmentosus, can be associated with notable abnormal systemic features. We believe that the incidence of associated abnormal features described in previous studies is exaggerated owing to referral and reporting bias.

DESIGN: Retrospective review of case series.

SETTING: An ambulatory, university hospital, pediatric dermatology practice and a large, city hospital, pediatric dermatology clinic.

PATIENTS: Fifty-four children referred consecutively over a 5-year period for evaluation of segmental, linear, or swirled hypopigmentation and/or hyperpigmentation along the lines of Blaschko.

MAIN OUTCOME MEASURE: Incidence of associated abnormal systemic features.

RESULTS: Extracutaneous abnormal features were present in 16 (30%) of 54 children with aberrant pigmentation along the lines of Blaschko: in 9 (33%) of 27 with hypomelanosis of Ito, in 4 (31%) of 13 with linear and whorled nevoid hypermelanosis, in 1 (11%) of 9 with nevus depigmentosus, and in 2 (40%) of 5 with coexistent hypopigmentation and hyperpigmentation.

CONCLUSIONS: Pigmentary anomalies along the lines of Blaschko are associated with abnormal systemic features far less often than has been reported previously. These pigmentary anomalies should not be considered distinct syndromes but rather grouped as a heterogeneous collection of disorders indicative of underlying genetic mosaicism. Such a classification will allow better understanding and evaluation of affected persons.