The Koebner phenomenon or Köbner phenomenon (UK: , US: ), also called the Koebner response or the isomorphic response, attributed to Heinrich Köbner, is the appearance of skin lesions 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 caused by a genus of plants including poison ivy). 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
Still disease
Cutaneous leishmaniasis
Post kala azar dermal leishmaniasisA similar response occurs in pyoderma gangrenosum and Behcets 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.
The neurofibroma is a benign nerve-sheath tumor in the peripheral nervous system. Ovarian fibroma
It appears in the sex cord-stromal tumour group of ovarian neoplasms. Ovary fibromas are most frequent during middle age, and rare in children. Upon gross pathological inspection, ovary fibromas are firm and white or tan. Variants with edema are especially likely to be associated with Meigs syndrome. On microscopic examination, there are intersecting bundles of spindle cells producing collagen. There may be thecomatous areas (fibrothecoma). The presence of an ovarian fibroma can cause ovarian torsion in some cases. Treatment
Benign fibromas may, but need not, be removed. Removal is usually a brief outpatient procedure or using cryotherapy in which the lesion is deep frozen (-196 degrees Celsius using liquid nitrogen) and thawed for two or more cycles, with full recovery within 3 to 4 weeks. The cryotherapy treatment needs no anesthetics and is painless. Another simple treatment is snip removal after injecting local anesthetic. See also
Acrochordon (skin tags)
Fibrous lesions

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