CLL is characterized by?
**Core Concept**
Chronic Lymphocytic Leukemia (CLL) is a type of cancer that affects the blood and bone marrow, characterized by the abnormal proliferation of mature lymphocytes. CLL is a malignancy of the B-cell lineage, involving the uncontrolled growth of clones of mature B lymphocytes.
**Why the Correct Answer is Right**
CLL is characterized by the accumulation of mature, but functionally incompetent B lymphocytes in the bone marrow, peripheral blood, and lymphoid organs. The malignant B cells in CLL are typically CD5+, CD23+, and CD38+, which distinguishes them from normal B cells. The accumulation of these cells leads to a decrease in the production of normal blood cells, including platelets and red blood cells.
**Why Each Wrong Option is Incorrect**
**Option A:** CLL is not typically characterized by an increase in blast cells, which is more typical of acute leukemias.
**Option B:** CLL is not primarily a disorder of the T-cell lineage, but rather involves B cells.
**Option C:** CLL is not characterized by a high degree of anaplasia or cellular atypia, which is more typical of aggressive lymphomas.
**Clinical Pearl / High-Yield Fact**
CLL is often diagnosed incidentally in asymptomatic patients, and a key feature of the disease is its slow progression, although some patients may progress rapidly. Treatment of CLL typically involves a watchful waiting approach, with interventions reserved for patients with symptomatic disease or significant cytopenias.
**Correct Answer: D. CLL is characterized by the accumulation of mature, but functionally incompetent B lymphocytes in the bone marrow, peripheral blood, and lymphoid organs.