Question: Which are the causes of the Koebner phenomenon?

Context:
Lichen sclerosus has been reported at sites of injury as a Koebner phenomenon. 
Therefore, lower expression of keratinocyte-derived factors, including SCF, in vitiliginous keratinocytes, which could result from keratinocyte apoptosis, might be responsible for passive melanocyte death and may explain the Koebner phenomenon.
Deprivation of survival factors causes the apoptosis of melanocytes. Vitiligo often develops following physical trauma, even if this is minor. The exact mechanism of the Koebner phenomenon in vitiligo is unclear.
First described in 1877 as the appearance of psoriatic lesions in the uninvolved skin of psoriatic patients as a consequence of trauma, the Koebner phenomenon has since been described in numerous diseases. 
The Koebner phenomenon is known to occur (lichen sclerosus occurs in skin already scarred or damaged), so trauma, injury, and sexual abuse have been suggested as possible triggers of symptoms in genetically predisposed people. 
The triggering role of physical stress is seen in the "deep Koebner" phenomenon, which causes inflammation in the synovial membrane and in enthesis, resulting in peripheral arthritis. 
The triggering role of physical stress is seen in the "deep Koebner" phenomenon, which causes inflammation in the synovial membrane and in enthesis, resulting in peripheral arthritis.
Two patients with unusual skin stimuli causing koebner phenomenon in psoriasis are reported.
To document the role of striae distensae and striae gravidarum in causing Koebner phenomenon in cases of vitiligo, psoriasis and lichen planus.
In addition, psoriasis can be caused by a local cutaneus trauma, known as Koebner phenomenon.
Striae are documented to cause Koebner phenomenon in patients with preexisting vitiligo, psoriasis and lichen planus, the three conditions where 'true kobenerisation' has been suggested according to Boyd and Nelder classification.
[Unusual Koebner phenomenon in psoriasis caused by varicella and UVB].
A 48 year-old woman developed an exacerbation of a latent psoriasis as a Koebner phenomenon in a migrating erythema caused by Borrelia afzelii infection.
[Psoriasis as Koebner phenomenon in erythma migrans].
[Characteristics of the Koebner phenomenon in patients with psoriasis vulgaris].
Vitiligo appearing in striae distensae as a Koebner phenomenon.
The appearance of vitiligo in striae distensae as a form of Koebner phenomenon has been reported rarely.
The Koebner phenomenon originally described the appearance of psoriatic lesions in the uninvolved skin of patients with psoriasis as a consequence of trauma.
The triggering role of physical stress is seen in the "deep Koebner" phenomenon, which causes inflammation in the synovial membrane and in enthesis, resulting in peripheral arthritis
To document the role of striae distensae and striae gravidarum in causing Koebner phenomenon in cases of vitiligo, psoriasis and lichen planus.Striae are documented to cause Koebner phenomenon in patients with preexisting vitiligo, psoriasis and lichen planus, the three conditions where true kobenerisation has been suggested according to Boyd and Nelder classification.Striae distensae and striae gravidarum are examples of blunt trauma
[Unusual Koebner phenomenon in psoriasis caused by varicella and UVB]
A 48 year-old woman developed an exacerbation of a latent psoriasis as a Koebner phenomenon in a migrating erythema caused by Borrelia afzelii infection
Intradermal antigen tests and the Koebner phenomenon in psoriasis
In addition, intensity of delayed hypersensitivity reaction and resolution times demonstrate no significant difference between psoriatic and nonpsoriatic subjects statistically (P > 0.05).These findings may indicate that intradermal antigens used in this study were more effective in inducing the Koebner phenomenon than injury alone
RESULTS: Striae are documented to cause Koebner phenomenon in patients with preexisting vitiligo, psoriasis and lichen planus, the three conditions where 'true kobenerisation' has been suggested according to Boyd and Nelder classification. 
According to the presence of Koebner phenomenon they were divided in two groups, one with positive and the other with negative Koebner phenomenon which presented the control group at the same time.RESULTS AND DISCUSSION: The Koebner reaction is often thought to be more frequent in actively spreading, severe psoriasis.
We describe a case of concurrent lichen planus and sarcoidosis in the auditory canal, which represents an unusual manifestation of the Koebner phenomenon.
According to the presence of Koebner phenomenon they were divided into two groups, 20 patients with positive and 40 patients with negative Koebner reaction, who were the control group at the same time.RESULTS AND DISCUSSION: 95% of patients treated with PUVA, were cleared of psoriatic changes in the Koebner positive, as well as in the Koebner negative group.
Striae are documented to cause Koebner phenomenon in patients with preexisting vitiligo, psoriasis and lichen planus, the three conditions where 'true kobenerisation' has been suggested according to Boyd and Nelder classification.

Answer: The causes of the Koebner phenomenon are:
1) Lichen sclerosus
2) Vitiligo
3) Psoriasis and 
4) Physical stress.
Exact answer: Lichen sclerosus, Vitiligo, Psoriasis, Physical stress, Lichen planus