Blaschko lines

Line system of the skin first described by Blaschko, followed by certain congenital skin anomalies (e.g. systematized epidermal nevi, ILVEN, nevoid hypertrichosis , incontinentia pigmenti, Bloch-Sulzberger type, Goltz-Gorlin syndrome).

A distinction is made between 2 types of Blaschko lines:

• Narrow bands (e.g. in incontinentia pigmenti). Type 1a
• Broad bands (e.g. in Albright syndrome). Type 1b

The lines are similar to the dermatome borders, but differ from these in that they rise steeply on the back and fall back down again in an arc and form S-shaped figures on the abdomen and flanks. On the arms and legs they run in a vertical direction. On the head and neck they form a complicated system in which the lines can cross over each other.

Blaschko lines correspond to the path embryonic cells take as they grow from the dorsal midline to the ventral side.

In the case of somatic mutations(cutaneous mosaic), the spread of the affected cell clone is visualized by the corresponding linear hamartoma (nevus).

1. Cambiaghi S (2000) Clinical findings in mosaic carriers of hypohidrotic ectodermal dysplasia. Arch Dermatol 136: 217-224
2. Happle R (1977) Genetic significance of the Blaschko lines. Z Hautkr 52: 935-944
3. Lipsker D (2000) Genetic mosaicism in an acquired inflammatory dermatosis following the lines of Blaschko. Arch Dermatol 136: 805-807
4. Lotfi M et al (2001) Off-center fold: linear atrophy, telangiectases, and soft nodules along the lines of Blaschko with skeletal abnormalities. Arch Dermatol 137: 1095-1100