Blaschko's lines

Blaschko's Lines, named after the German dermatologist Alfred Blaschko, represent pathways of embryonic cell migration during the development of the skin. Under normal circumstances, these lines are invisible and only become visible when certain skin disorders, typically those of a genetic or mosaic nature, manifest along these patterns.

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Blaschko's lines, patterns female-male front-back 3d-shaded

Discovery

Alfred Blaschko first demonstrated these lines in 1901, not based on dissection or inspection of skin tissues, but by meticulously noting and sketching patterns of skin rashes and moles on his patients.

Characteristics

Blaschko's lines do not correspond to nervous, muscular, or lymphatic systems, but rather seem to follow the pattern of cell migration during embryonic development. They form a 'V' shape on the back, 'S' shaped spirals on the chest and sides, and wavy shapes on the head.

Clinical Significance

Blaschko's lines are significant in the field of dermatology and genetic medicine as they can provide clues to the nature of skin diseases and conditions.

Mosaic Disorders: Many skin disorders, such as Incontinentia Pigmenti, Lichen Striatus, and Epidermal Nevus Syndrome, which have a genetic mosaicism, manifest along Blaschko's lines. Mosaicism refers to the occurrence of two or more populations of cells with different genotypes in one individual, developed from a single fertilized egg.

X-linked Skin Disorders: Certain X-linked skin disorders, such as Goltz syndrome, also appear to follow Blaschko's lines. This is because these lines represent the clonal expansion of cells from the ectodermal layer during embryogenesis, and highlight the pattern of X-chromosome inactivation.

See Also

• Dermatology
• Genetics
• Alfred Blaschko
• Skin

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