Sammendrag
Background: Pruritus, or itch, is defined as an unpleasant sensation of the skin leading to the desire to scratch. Pruritus is most commonly seen as a part of skin disease, but sometimes this bothering symptom can be a feature of malignancy. Malignant diseases are frequent, and approximately one in three Norwegians will get cancer during their lifetime. Objective: The aim of the paper is to give an overview on pruritus associated with malignant disease and to discuss findings in the literature. Method: The work is based on nonsystematic searches in PubMed, dermatological encyclopedias and other, web based resources. Results: Some malignancies are associated with pruritus through various mechanisms, either as direct involvement of the skin, as part of paraneoplastic phenomena or because of invasive growth into organs or nerves. The extent to which pruritus is present is highly variable, but the incidence is high especially in some hematological malignancies and in those causing cholestasis. Pruritus is less frequently associated with cutaneous metastatis. The pruritus can have several different clinical presentations. Exact mechanisms are usually unknown, and treatment directed towards the malignancy will often reduce the symptom. Conclusion: Itching can be a feature of different malignant diseases and can sometimes precede the diagnosis by months or years. Evaluating all pruritic patients for cancer is probably impossible, but after having excluded the normal causes of itching, an individual assessment should be made. Although the symptom is rare, knowledge about these findings may lead to an earlier diagnosis and to earlier treatment of cancer.