ALK-1-negative anaplastic large-cell lymphoma presenting as a dura-based mass in an infant.

Introduction Anaplastic large-cell lymphoma (ALCL) rarely occurs in the central nervous system in the pediatric population. Case presentation We describe a diagnostically challenging case of an 11-month-old infant presenting with cranial nerve palsies and peripheral eosinophilia. Imaging demonstrated meningeal thickening with enhancement and dura-based deposits, the biopsy of which revealed features of ALK-1 negative ALCL on histologic and immunophenotypic analysis. A thorough investigation excluded the possibility of any extra-cranial origin. Hence, a diagnosis of "primary" ALCL was rendered. Conclusion ALCL arising in the dura in an infant has not been described earlier, to the best of our knowledge.