A Reed-Sternberg cell is a large, abnormal cell typically found in lymphatic tissue. It is a key characteristic of Hodgkin lymphoma, a type of cancer that affects the lymphatic system. These cells are often multinucleated, meaning they have more than one nucleus, and they can be identified under a microscope due to their distinctive appearance. The presence of Reed-Sternberg cells is crucial for diagnosing Hodgkin lymphoma. They arise from B lymphocytes, a type of white blood cell, and their abnormal growth leads to the symptoms associated with this disease, such as swollen lymph nodes, fever, and weight loss.