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A target lesion is an area of abnormal skin that has the appearance of a target or a bull's-eye. It typically looks like a rash or an eruption of the skin that has a red center with a red ring encircling the center. Commonly associated with Lyme disease, the target lesion may also be erythema multiforme (EM), which can be caused by many underlying conditions, such as a viral infection.
Lyme disease is a bacterial infection transmitted by the bite of a tick. It often presents with a target lesion surrounding the area of the tick bite, however not all infected people will develop this mark. This rash may appear several weeks to a month following the bite, and patients will also likely experience a fever, fatigue, and muscle or joint pain.
When a target lesion develops on the skin of a person infected with Lyme disease, it is called erythema migrans (EM). Some patients may also notice similar lesions appearing on other areas of the body, following the appearance of the initial mark. These lesions are generally bright red, with a solid, red circle enclosed by a red ring. Patients who notice this bulls-eye mark on the skin in the weeks following a tick bite should see their doctors as soon as possible for treatment with antibiotics.
In contrast to Lyme disease, the target lesion known as erythema multiforme is most often caused by a viral infection. The herpes simplex virus is a common culprit, and it may manifest with a lesion within two weeks of the initial infection. Other viral infections may also result in a target lesion, including hepatitis, chickenpox, and shingles, along with cytomegalovirus, parapoxvirus, and human immunodeficiency virus (HIV). Less commonly, some fungal infections or medications may also result in erythema multiforme. These drugs may include nonsteroidal anti-inflammatory drugs (NSAIDs), anticonvulsants, and barbiturates.
Patients with erythema multiforme will notice dozens or hundreds of small target lesions. They typically begin to develop on the hands and feet, and spread toward the center of the body. Over the course of about 72 hours, the lesions will change from being flat, red marks to raised patches with darker centers, surrounded by a lighter, pink area, which in turn is surrounded by a bright red mark.
These kinds of target lesions will often go away on their own over the course of several weeks. Some patients may require treatment, depending on the underlying cause of the skin condition. Antiviral drugs like acyclovir or erythromycin may resolve the lesions. Patients who suffer from skin itching may benefit from topical corticosteroids or oral antihistamines.