Phakomatosis pigmentovascularis type IIb in association with external hydrocephalus.

Phakomatosis pigmentovascularis (PPV) is a rare sporadic genetic disorder characterised by co-occurrence of an extensive vascular nevus and a large pigmentary nevus with or without extracutaneous manifestations. There are four types of PPV with subtype 'a' for cutaneous involvement only and subtype 'b' for cutaneous and systemic involvement. PPV type IIa consists of nevus flammeus, Mongolian spots and sometimes nevus anemicus. Prognosis depends on associated systemic disorders. Two independent cases of PPV type IIb presented with nevus flammeus, aberrant Mongolian spots, ocular and central nervous system anomalies. Case 1 had external hydrocephalus previously unreported in PPV while case 2 had hydrocephalus exvacuo. Both patients had seizure disorder and neurodevelopmental delay. They were on long-term neurologic and ophthalmologic management while their cutaneous lesions partially regressed. PPV affects all racial and ethnic groups. The occurrence of external hydrocephalus in PPV expands the spectrum of its systemic manifestations.