Which phenomenon describes the appearance of new skin lesions at sites of trauma in conditions like lichen planus?

Köebner's phenomenon, also known as the Köebner response, refers to the development of new skin lesions in response to trauma or injury to the skin in certain dermatological conditions, such as lichen planus, psoriasis, and vitiligo. This phenomenon occurs when the trauma disrupts the skin barrier, triggering an inflammatory response that leads to the formation of lesions in previously unaffected areas.

In the context of lichen planus, the presence of Köebner's phenomenon illustrates the autoimmune nature of the disease, where trauma leads to an immune-mediated response that results in the characteristic lesions associated with lichen planus. This is particularly notable as it helps clinicians recognize and understand the behavior of certain skin conditions and can assist in diagnosing and managing them effectively.

Other options, such as the bullous phenomenon, urticaria, and striae gravidarum, do not describe this trauma-induced response. The bullous phenomenon relates to blistering diseases, urticaria is associated with hives due to allergic reactions, and striae gravidarum refers to stretch marks often seen during pregnancy. None of these concepts align with the mechanism of lesion formation seen in Köebner's phenomenon.