nervous system benign neoplasm melanocytic nevus phakomatosis pigmentokeratotica https://github.com/monarch-initiative/mondo/issues/6877 https://www.malacards.org/card/phakomatosis_pigmentokeratotica Orphanet:2874 MESH:C537893 UMLS:C2931658 Phacomatosis pigmentokeratotica SCTID:723455009 GARD:0004311 MONDO:0017317 Phakomatosis pigmentokeratotica (PPK) is a very rare epidermal nevus disorder characterized by the association of speckled lentiginous nevi with epidermal sebaceous nevi, and extracutaneous anomalies. MEDGEN:419860 icd11.foundation:960559196 organoid nevus with sebaceous differentiation, a speckled-lentiginous nevus, and other associated anomalies developmental defect during embryogenesis neurocutaneous syndrome hereditary skin disorder hereditary neurological disease