Lymphomatoid papulosis (LyP) is a non-contagious, chronic skin condition characterized by the eruption of recurring, self-healing bumps (lesions) on the skin. The lesions typically begin small and then become larger, and they may bleed or ulcerate before becoming scaly and crusty. They often develop a red-brown color. Symptoms associated with lesions may include itching and/or pain, which may be debilitating. The frequency of eruptions varies over time and from person to person. Lesions may be very persistent, or they may go away for long periods of time before coming back. They may occur anywhere on the body, but they typically develop on the trunk, arms, and legs, and may develop on the hands, face, and genitalia. They generally go away on their own over a period of weeks to months (usually between 3 and 8 weeks), with or without scarring. LyP is not contagious. The cause of LyP is not known, but there is no evidence that it is hereditary. Stress is often reported to trigger eruptions of lesions. A diagnosis of LyP requires evaluating the symptoms and having a skin biopsy for various types of laboratory tests. While LyP usually is not classified as a cancer (although there has been some debate), it has characteristics of lymphoma under the microscope, and people with LyP have a life-long increased risk of developing lymphoma such as mycosis fungoides, PC-ALCL, or Hodgkin lymphoma. In 5 to 20 percent of people with LyP, the condition is either preceded by lymphoma, associated with lymphoma, or followed by lymphoma. When LyP is diagnosed it is important to rule out these cancers, and for this reason, various blood tests or imaging studies may also be recommended.