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The Koebner phenomenon or Köbner phenomenon (, ), also called the Koebner response or the isomorphic response, attributed to Heinrich Köbner, is the appearance of
skin lesion A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of this ...
s on lines of trauma. The Koebner phenomenon may result from either a linear exposure or irritation. Conditions demonstrating linear lesions after a linear exposure to a causative agent include: molluscum contagiosum, warts and toxicodendron dermatitis (a
dermatitis Dermatitis is a term used for different types of skin inflammation, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened ...
caused by a genus of plants including
poison ivy Poison ivy is a type of allergenic plant in the genus '' Toxicodendron'' native to Asia and North America. Formerly considered a single species, '' Toxicodendron radicans'', poison ivies are now generally treated as a complex of three separate s ...
). Warts and molluscum contagiosum lesions can be spread in linear patterns by self-scratching (" auto-inoculation"). Toxicodendron dermatitis lesions are often linear from brushing up against the plant. Causes of the Koebner phenomenon that are secondary to scratching rather than an infective or chemical cause include vitiligo, psoriasis, lichen planus, lichen nitidus, pityriasis rubra pilaris, and keratosis follicularis (Darier disease).


Definition

The Koebner phenomenon describes skin lesions which appear at the site of injury. It is seen in: :* Psoriasis :* Pityriasis rubra pilaris :* Lichen planus :* Flat warts :* Lichen nitidus :* Vitiligo :* Lichen sclerosus :* Elastosis perforans serpiginosa :* Kaposi sarcoma :* Necrobiosis lipoidica :* Lupus :*
Juvenile Idiopathic Arthritis Juvenile idiopathic arthritis (JIA), formerly known as juvenile rheumatoid arthritis (JRA), is the most common chronic rheumatic disease of childhood, affecting approximately 3.8 to 400 out of 100,000 children. ''Juvenile'', in this context, ref ...
:* Still disease :* Cutaneous leishmaniasis :* Post kala azar dermal leishmaniasis :* Eruptive xanthomas :* Urticaria A similar response occurs in pyoderma gangrenosum and Behcet's syndrome, and is referred to as pathergy. Rarely Koebner phenomenon has been reported as a mechanism of acute myeloid leukemia dissemination. Warts and molluscum contagiosum are often listed as causing a Koebner reaction, but this is by direct inoculation of viral particles. The linear arrangement of skin lesions in the Koebner phenomenon can be contrasted to both lines of Blaschko and dermatomal distributions. Blaschko lines follow embryotic cell migration patterns and are seen in some mosaic genetic disorders such as incontinentia pigmenti and pigment mosaicism. Dermatomal distributions are lines on the skin surface following the distribution of spinal nerve roots. The rash caused by herpes zoster ( Shingles) follows such dermatomal lines.


History

The Koebner phenomenon was named after the rather eccentric but renowned German dermatologist Heinrich KoebnerIn the
anglicisation Anglicisation or anglicization is a form of cultural assimilation whereby something non-English becomes assimilated into or influenced by the culture of England. It can be sociocultural, in which a non-English place adopts the English language ...
of a German word, double vowels are often substituted for the
Germanic umlaut The Germanic umlaut (sometimes called i-umlaut or i-mutation) is a type of linguistic umlaut (linguistics), umlaut in which a back vowel changes to the associated front vowel (fronting (phonology), fronting) or a front vowel becomes closer to ...
on single vowels. The transformation of "Köbner" to "Kooebner" is just such a case. In the English literature, the umlaut is simply dropped and you often find "Köbner" simply as "Kobner".
(1838–1904). Koebner is best known for his work in
mycology Mycology is the branch of biology concerned with the study of fungus, fungi, including their Taxonomy (biology), taxonomy, genetics, biochemistry, biochemical properties, and ethnomycology, use by humans. Fungi can be a source of tinder, Edible ...
. His intense nature is illustrated by the following: in a medical meeting, he proudly exhibited on his arms and chest three different fungus infections, which he had self-inoculated, in order to prove the infectiousness of the organisms he was studying. The Koebner phenomenon is the generalized term applied to his discovery that on psoriasis patients, new lesions often appear along lines of trauma.


See also

* Renbök phenomenon


References


Sources

* Crissey JT, Parish LC, Holubar KH. Historical Atlas of Dermatology and Dermatologists. New York: The Parthenon Publishing Group, 2002. * Paller A, Mancini A. Hurwitz Clinical Pediatric Dermatology. Philadelphia: Elsevier Saunders, 2002. {{DEFAULTSORT:Koebner Phenomenon Dermatologic signs