Intravascular lymphomatosis (IL) in a child mimicking a posterior fossa tumor.

Intravascular lymphomatosis (IL) is a rare entity only recently included in lymphoma classification, whose main feature is the exclusive or predominant growth of neoplastic cells within blood vessels. The vast majority of the patients affected by IL belong to the 7th or 8th decade of life and present with skin rash or CNS diffuse necrotic or demyelinating lesions. Case report. SS, a 13-year-old girl, was admitted to a Neurosurgery Unit because of endocranic hypertension, where, after CT and MRI documenting a IV ventricle 3 cm diameter tumor, she was submitted to complete tumor excision: extemporary diagnosis was suggestive of medulloblastoma. When referred to us she had persistent fever with normal blood and spinal fluid cultures. Whole CNS MRI did not give evidence of residual or metastatic disease while CSF cytology showed only pleiocytosis. Treatment was started according to our ongoing protocol for medulloblastoma with pre-radiation chemotherapy. Before delivering radiotherapy (RT), upon review of histologic specimens, the definitive diagnosis of IL B-phenotype was made. The girl was re-admitted and, after a complete re-staging, chemotherapy was intensified according to our schedule for high-grade B-cell lymphoma and CNS was irradiated up to a total dose of 25 Gy. She remained alive in continuous complete remission at 21 months after diagnosis. The case here reported is unique for age, tumor presentation, and, so far, favourable outcome, in spite of the delayed histological diagnosis.