Which of the following is a common presenting symptom in a patient with chronic neutrophilic leukemia (CNL)?

In chronic neutrophilic leukemia (CNL), fever is indeed a common presenting symptom. This is often linked to the underlying disease process, as patients with CNL can experience persistent low-grade fever due to inflammation or infection, both of which can accompany the disease. Chronic neutrophilic leukemia is characterized by an increase in neutrophils in the blood, which can also contribute to systemic symptoms including febrile responses. The presence of fever can indicate that the body is reacting to the increased cell turnover or possibly to opportunistic infections, which can arise in cases of hematologic malignancies.

While fatigue, marked lymphadenopathy, and splenomegaly can also be symptoms seen in various hematologic disorders, they are not as directly associated with CNL as fever is. Fatigue can occur due to many reasons, including anemia or other factors, and while splenomegaly can be noted in some cases, it is not as definitive in CNL as fever may be. Marked lymphadenopathy is more characteristic of other leukemias or lymphoproliferative disorders, but it is not a typical presenting symptom of CNL. Thus, fever stands out as a more common and defining symptom in this specific condition.