Final answer:
Chronic Lymphocytic Leukemia (CLL) is diagnosed by identifying abnormal lymphocytes, often using flow cytometry to detect specific cell surface markers present on B lymphocytes. While lymphoma also involves malignant lymphocytes, its diagnosis requires a biopsy and immunohistochemistry to determine the affected lymphocyte subtype.
Step-by-step explanation:
Chronic Lymphocytic Leukemia (CLL) is characterized by the accumulation of mature lymphocytes, which fail to die, interrupting normal immune system function. Diagnosing CLL involves identifying these abnormal cells through blood tests, and often, flow cytometry is used to detect specific cell surface markers characteristic of CLL cells such as CD19, CD20, CD23, and CD5 which are typically present on B lymphocytes. The presence of these markers, along with an increased lymphocyte count in the blood, suggests CLL.
Lymphoma, another form of lymphocyte cancer, requires tissue biopsy for diagnosis. The biopsy sample is examined under a microscope to observe abnormal cell size or shape, and immunohistochemistry techniques are utilized to detect the presence of specific antigens on the surface of the cancerous lymphocytes. Determining these markers is essential for distinguishing between the different types of lymphoma, such as T-cell or B-cell lymphoma.