Unusual relapse of primary central nervous system lymphoma both inside and outside central nervous system in a patient with ventriculoperitoneal shunt: a case report.

BACKGROUND: Relapse of primary central nervous system (CNS) lymphoma (PCNSL) occurs primarily at the initial site. Relapse outside the CNS is rare. CASE DESCRIPTION: We present the case of a 62-year-old immunocompetent man who underwent a stereotactic biopsy to diagnose PCNSL and subsequent placement of ventriculoperitoneal shunt (VPS) for symptom relief in November 2012. He got complete remission after 6 cycles of high-dose methotrexate-based chemotherapy. In August 2017, relapse of lymphoma occurred in the abdomen, left basal ganglia, and bilateral ventricle with the largest lesion being around the VPS in the abdomen. He got complete remission after 6 cycles of R-CHOP (rituximab, cyclophosphamide, epirubicin, vincristine and prednisolone) plus 8 cycles of high-dose methotrexate chemotherapy. CONCLUSIONS: Here we report the first case of extra-CNS relapse of PCNSL around the site of VPS in the abdomen after intensive chemotherapy. Neuro-surgeons should be aware of a potential risk of PCNSL spread along the VPS.