Target Volume Delineation for Extramedullary Leukemia

Extramedullary (EM) manifestations of acute leukemia include a wide variety of clinically significant phenomena, which often pose therapeutic challenges. Myeloid sarcoma (MS) and leukemia cutis (LC) represent two well-known EM manifestations that have a range of clinical presentations. MS (also known as granulocytic sarcoma or chloroma) is a rare EM tumor of immature myeloid cells. LC specifically refers to the infiltration of the epidermis, dermis, or subcutis by neoplastic leukocytes (leukemia cells) resulting in clinically identifiable cutaneous lesions. In this chapter, we summarize the use of radiation therapy to treat MS.