**Question:** Examination of a peripheral blood smear demonstrates a leukemia composed of small mature lymphocytes without blast forms. Which of the following is the most likely age of this patient?

A. Childhood
B. Adolescence
C. Young adults
D. Middle age

**Core Concept:** Leukemias are a group of blood cancers characterized by the uncontrolled proliferation of abnormal white blood cells. In this question, we are dealing with a leukemia involving mature lymphocytes without blast forms.

**Why the Correct Answer is Right:** The correct answer, D. Middle age, is due to the fact that the majority of leukemia cases involving mature lymphocytes occur in adults, with a peak incidence in the 40-60 age range. While childhood leukemia is also common, the presence of small mature lymphocytes without blast forms indicates a more mature form of leukemia.

**Why Each Wrong Option is Incorrect:**

A. Childhood: While childhood leukemia is a possibility, the absence of blast forms suggests a more mature form of leukemia, which is more common in adults.
B. Adolescence: Similar to childhood leukemia, this option is also possible, but the presence of small mature lymphocytes without blast forms favors a more mature form of leukemia, which is more common in adults.
C. Young adults: This option is incorrect for the same reasons as options A and B, as the absence of blast forms suggests a more mature form of leukemia, which is more common in adults.

**Clinical Pearl:** The presence of small mature lymphocytes without blast forms in a peripheral blood smear is more suggestive of a mature lymphoproliferative disorder, such as chronic lymphocytic leukemia (CLL). CLL is a type of leukemia characterized by the accumulation of mature lymphocytes and is commonly seen in the middle-aged and elderly population.

**Correct Answer:** D. Middle age