Phacomatosis spilosebacea: A new name for a distinctive binary genodermatosis.

Area of Science:

• Dermatology
• Genetics
• Medical Syndromes

Background:

• Phacomatosis pigmentokeratotica (PPK) is characterized by nevus spilus and sebaceous nevus along Blaschko's lines.
• Previous literature describes PPK as a distinct entity, but its precise classification and etiology require further clarification.

Purpose of the Study:

• To propose a new nomenclature for PPK, renaming it phacomatosis spilosebacea (PSS).
• To elucidate the genetic basis and associated extracutaneous abnormalities of PSS.

Main Methods:

• Systematic literature review of 95 established PPK cases.
• Analysis of genetic mutations and phenotypic manifestations, including extracutaneous abnormalities.

Main Results:

• Mosaic HRAS gene mutations are identified as the sole confirmed cause of PSS.
• Extracutaneous abnormalities, including those seen in Schimmelpenning syndrome and nevus spilus syndrome, are present in approximately 75% of cases.
• PSS is associated with a high risk of basal cell carcinoma, urogenital malignancies, and vitamin D-resistant hypophosphatemic rickets.

Conclusions:

• The proposed renaming to phacomatosis spilosebacea (PSS) better reflects the condition's key features.
• Understanding the genetic basis and associated risks is crucial for managing PSS patients.