Keratinocytic epidermal nevi are associated with mosaic RAS mutations.

Background: Activating RAS mutations in the germline cause rare developmental disorders such as Costello syndrome. Somatic RAS mutations are found in approximately 30% of human cancers. Keratinocytic epidermal nevi (KEN) represent benign congenital skin lesions arranged along Blaschko's lines.

Cell and tissue interactions of Treponema pallidum in primary and secondary syphilitic skin lesions: an ultrastructural study of serial sections.

There are limited reports on the ultrastructure of syphilis skin lesions. The aim of this study has been to perform an electron microscopic investigation of the morphology and the tissue distribution of treponemes in primary and secondary cutaneous lesions. Three cases of primary syphilitic chancre and one case of secondary syphilis were included.

Multiple oncogenic mutations and clonal relationship in spatially distinct benign human epidermal tumors.

Malignant tumors result from the accumulation of genetic alterations in oncogenes and tumor suppressor genes. Much less is known about the genetic changes in benign tumors. Seborrheic keratoses (SK) are very frequent benign human epidermal tumors without malignant potential.