Primary Central Nervous System Lymphoma is a rare extranodal non-Hodgkin lymphoma, primarily arising in brain and spinal cord tissue, leptomeninges and vitreoretinal eye. Pediatric PCNSLs are even rarer. We describe the case of a boy presenting with seizures and a suspected brain meningioma, but a final diagnosis of ALK+ Anaplastic Large Cell Lymphoma. We conducted a qualitative systematic review following the ENTREQ framework on pediatric cases of PCNSL, identifying only nine cases of brain ALCL. Our work describes the high frequency of misdiagnosis correlating with poor prognosis, and highlights the importance of a multidisciplinary approach considering ALCL among differential diagnosis.