Modern sun protection.

So far sun protection meant ultraviolet (UV) protection. But there is preliminary data that beside UV radiation also visible light (VIS) and near infrared A (IRA) radiation may have harmful effects on our skin resulting in photoaging and even cancer induction. Therefore, some authors claim that modern sun protection should also include shielding against longer wavelengths such as VIS and IRA.

Phototherapie.

Die Phototherapie nutzt die photobiologische Wirkung von ultravioletter (UV-)Strahlung auf unseren Organismus. Die verschiedenen Wellenlängen der Strahlung rufen dabei ganz unterschiedliche Effekte hervor. Der gezielte Einsatz von UV-A und UV-B, gegebenenfalls auch in Kombination mit dem Photosensibilisator Psoralen im Rahmen einer PUVA-Therapie, ermöglicht dem Dermatologen die effektive Behandlung der verschiedensten Hautkrankheiten.

Phototherapy.

The efficacy of phototherapy is based on the interaction between ultraviolet (UV) radiation and the skin. The photobiological effects thus achieved depend on the wavelengths used. Targeted use of UVA and UVB, where indicated in combination with a photosensitizer such as psoralen, provides the dermatologist with a broad armamentarium for the treatment of a multitude of skin diseases.

KRAS, HRAS and EGFR Mutations in Sporadic Sebaceous Gland Hyperplasia.

Sporadic sebaceous gland hyperplasia (SGH) is a benign skin lesion, with a high prevalence in the general population. Although SGH has been attributed to both extrinsic and intrinsic factors, the underlying genetic changes have not yet been characterized. Recently, HRAS and KRAS mutations have been identified in sebaceous naevus, a hamartoma sharing histological characteristics with SGH.

Phacomatosis pigmentokeratotica is caused by a postzygotic HRAS mutation in a multipotent progenitor cell.

Phacomatosis pigmentokeratotica (PPK) is a rare epidermal nevus syndrome characterized by the co-occurrence of a sebaceous nevus and a speckled lentiginous nevus. The coexistence of an epidermal and a melanocytic nevus has been explained by two homozygous recessive mutations, according to the twin spot hypothesis, of which PPK has become a putative paradigm in humans. However, the underlying gene mutations remained unknown.

Postzygotic HRAS and KRAS mutations cause nevus sebaceous and Schimmelpenning syndrome.

Nevus sebaceous is a common congenital cutaneous malformation. Affected individuals may develop benign and malignant secondary tumors in the nevi during life. Schimmelpenning syndrome is characterized by the association of nevus sebaceous with extracutaneous abnormalities.