This monograph includes five chapters about neurofibromatosis type 1 (NF1), a condition characterized by changes in skin coloring and the growth of tumors along nerves in the skin, brain, and other parts of the body. Chapter One concerns the evolving molecular biology, targeted therapeutics, and neurocognitive deficits in neurofibromatosis type one. Chapter Two focuses on gastrointestinal stromal tumors and reviews the clinicopathologic features of these tumors and discusses differential diagnostic considerations. Chapter Three explores juvenile myelomonocytic leukemia, a rare hematological...