Phakomatosis Pigmentovascularis Type IIB: a case report.

Phakomatosis Pigmentovasularis (PPV) is a rare condition defined by the presence of both vascular and melanocytic nevi occurring in the same patient. We report the case of a 27-year-old Chinese female who presented with generalized port-wine stains over the left trigeminal region, trunk, and limbs, diffuse dermal melanosis on the back, nevus of Ota on the right cheek, and scleral melanosis. Her port-wine stain on the trunk was distributed in a checker-board pattern. She was otherwise well. She was diagnosed with phakomatosis pigmentovascularis (PPV) Type IIb. The 'twin spotting' phenomenon has been proposed in the pathogenesis of PPV, and PPV is an example of non-alleleic twin spotting. The checkerboard distribution of port-wine stain in our patient follows the type II pattern of distribution in cutaneous mosaics. This lends further credence to the proposed hypothesis of twin spotting and cutaneous mosaicism in the pathogenesis of PPV.