Most common non-CNS malignancy in children:

• A. Posterior fossa
• B. Lambert-Eaton myasthenic syndrome
• C. Acute lymphoblastic leukemia
• D. Glioblastoma

Answer: (A)

Leukemia is the most common cancer in children, and when the question asks for the most common non-CNS malignancy, acute lymphoblastic leukemia fits as the top choice because it is a hematologic cancer outside the central nervous system.

Posterior fossa is simply an area of the brain, not a disease itself, so it cannot be the malignancy being described. Lambert-Eaton myasthenic syndrome is a paraneoplastic condition, not a primary cancer, and it’s uncommon in children. Glioblastoma is a CNS tumor, which would be excluded by the “non-CNS” qualifier and is also less common in the pediatric population compared with leukemia.