Evolution of a Pediatric Primary Cerebral ALK-1-Positive Anaplastic Large Cell Lymphoma on Serial MRI.

BACKGROUND: Primary central nervous system lymphoma (PCNSL) is a rare central nervous system tumor, especially in the pediatric population. There are fewer than 20 described cases of pediatric primary central nervous system anaplastic large cell lymphoma. The child described in our case report demonstrated a dramatic evolution of this tumor in the first 4 weeks on serial imaging. METHODS: Serial MRI imaging was performed followed by biopsy and chemotherapy. RESULTS: Initial imaging revealed a T2 hyperintense lesion in the frontal lobe with abnormally enhancing sulci and minimal surrounding edema and diffusion restriction. Serial imaging revealed progressive increase in the degree of gadolinium enhancement, and the hyperintense T2 edema progressed markedly to exert mass effect. The lesion itself grew marginally. Biopsy revealed an anaplastic large cell lymphoma, only described in 14 previous pediatric patient case reports. The patient was successfully treated with chemotherapy and autologous stem cell transplant. CONCLUSIONS: Our case demonstrates the rapidity with which a PCNSL lesion can develop, and the evolution of the imaging characteristics prior to definitive diagnosis and treatment. Serial imaging by MRI may help differentiate the behavior of a PCNSL from other imitating lesions.