**Question:** The most characteristic radiographic sign in a child with leukemia is -

A. Increased lung markings
B. Mediastinal widening
C. Enlarged liver and spleen
D. Bilateral hilar lymphadenopathy

**Core Concept:** Leukemias are a group of blood cancers characterized by the uncontrolled proliferation of blood cells, often leading to the displacement of normal cells and organ dysfunction. Radiographic findings can provide valuable information about the disease process.

**Why the Correct Answer is Right:** The correct answer (C) is related to the infiltration of blood-forming tissues by leukemic cells. In children with leukemia, the leukemic cells can infiltrate the liver and spleen, leading to their enlargement. This is known as hepatosplenomegaly and is a common finding in leukemia.

**Why Each Wrong Option is Incorrect:**

A. Increased lung markings (A) could be seen in various conditions, including pneumonia, pulmonary edema, and fibrosis. It is not specific to leukemia.

B. Mediastinal widening (B) is a more common finding in lymphoma and other conditions rather than leukemia.

D. Bilateral hilar lymphadenopathy (D) is a characteristic finding in lymphoma and other lymphoproliferative disorders, not leukemia.

**Clinical Pearl / High-Yield Fact:**

Leukemias can present with various radiological findings depending on the type of leukemia, stage of disease, and organ involvement. It is essential for clinicians to recognize these findings to make an accurate diagnosis and initiate an appropriate treatment plan.

In summary, the correct answer (C) refers to the characteristic radiographic finding of hepatosplenomegaly in children with leukemia, while the wrong options represent findings in different conditions or are not specific to leukemia. In clinical practice, understanding these radiographic findings can aid in the diagnosis and management of leukemia cases.