Blaschko's lines, also called the Lines of Blaschko, are an extremely rare and unexplained phenomenon of human anatomy first presented in 1901 by German dermatologist Alfred Blaschko. Neither a specific disease nor a predictable symptom of a disease, Blaschko's lines are an invisible pattern built into human DNA. Many inherited and acquired diseases of the skin or mucosa manifest themselves according to these patterns, creating the visual appearance of stripes.

The cause of the stripes is thought to result from mosaicism; they do not correspond to nervous, muscular, or lymphatic systems. What makes them more remarkable is that they correspond quite closely from patient to patient, usually forming a "V" shape over the spine and "S" shapes over the chest, stomach, and sides.

It is theorized that the lines define the natural areas of growth between the original cells of the embryo and the later (copied) cells of mature adults.

Conditions distributed along Blaschko’s lines

A number of X-linked, congenital/naevoid and acquired skin diseases follow Blaschko’s lines. These have been extensively reviewed by Bolognia. Examples include:

• Pigmentary disorders
• Naevus achromicus (including hypomelanosis of Ito)
• Epithelial Naevi
• Sebaceous naevus
• Inflammatory linear verrucous naevus
• X-linked dominant skin disorders
• Incontinentia pigmenti
• CHILD syndrome
• Acquired skin disorders with polygenic aetiology
• Lichen striatus
• Linear lichen planus
• Linear lupus erythematosus

References

• A. Blaschko (1901). "Die Nervenverteilung in der Haut in ihre Beziehung zu den Erkrankungen der Haut". Beilage zu den Verhandlungen der Deutschen Dermatologischen Gesellschaft VII Congress, Breslau
• R. Jackson (1976). "The lines of Blaschko: a review and reconsideration: Observations of the cause of certain unusual linear conditions of the skin". The British Journal of Dermatology 95(4) 349–360.
• E. Hale (2001). "Acquired Blaschko Dermatitis". Dermatology Journal, Department of Dermatology, New York University 7(1) 8.
• Happle R, Assim A (2001). "The lines of Blaschko on the head and neck". Journal of the American Academy of Dermatology 44 612–615.
• Bolognia J L, Orlow S J, Gilick S G (1994). "Lines of Blaschko". Journal of the American Academy of Dermatology 31(2) 157–190.
• Scheinfeld S,Tarlow M, Burgin S (2003). "Blaschkoid eccrine spiradenomas, Cutis". 70 73–75.

External links

• Illustrations of the various patterns of cutaneous mosaicism
• Photo of the back of a young patient showing the characteristic "V" pattern
• Understanding Genetics - ask a geneticist
• Description of Blaschko's lines