ABSTRACT
Neoplastic reactions, including benign and malignant tumors, can be induced by different conventional chemotherapeutics and in particular by targeted cancer drugs. Regarding neoplastic reactions of the skin, subsequent malignant and in situ neoplasms in long-term cancer survivors are almost exclusively associated with radiotherapy. Yet, conventional cytotoxic chemotherapy, and in particular selected targeted cancer drugs, may cause a broad spectrum of benign and malignant neoplastic reactions. A nonmelanoma skin cancer (NMSC) of particular importance in cancer patients receiving BRAF-targeted therapies is the keratoacanthoma (KA). KAs develop as solitary, sometimes multiple, exophytic, dome-shaped tumors with a central ulceration that are characterized by a rapid growth over few weeks. NMSC is the most common subsequent neoplasms in long-term cancer survivors accounting for more than 40% of all confirmed SNs. In adults, the antimetabolite hydroxyurea (HU) has been associated to the development of multiple NMSCs. Discontinuation of HU is proposed to result in a resolution or at least improvement of respective tumors.
