Cutis verticis gyrata: three cases with different aetiologies that demonstrate the classification system.

Cutis verticis gyrata describes a scalp condition where there are convoluted folds and deep furrows that resemble the surface of the cerebral cortex. We report three cases of cutis verticis gyrata that demonstrate the current classification structure. The first case is the most commonly described primary non-essential acquired form, appearing in the scalp of an 11-year-old girl with mental retardation. The second case is the primary non-essential congenital form, presenting at birth in a baby with Noonan's syndrome. An association between cutis verticis gyrata and Noonan's syndrome has been rarely described. The third case illustrates secondary cutis verticis gyrata, occurring in a 27-year-old man with discoid eczema.