A rare case of paediatric primary central nervous system lymphoma treated with high-dose methotrexate and rituximab-based chemoimmunotherapy and whole brain radiotherapy followed by tumour bed boost with three-dimensional conformal radiation technique.

BACKGROUND: Primary central nervous system lymphomas (PCNSL) are rare in the paediatric population. CLINICAL CASE: A 12-year-old boy presented to our clinic with complaints of multiple episodes of generalised tonic-clonic seizures for 1 year and gradual loss of vision in both eyes for 3 months. Baseline magnetic resonance imaging (MRI) of the brain showed a large (7.2 × 7 cm) enhancing soft tissue lesion in the right frontal lobe causing mass effect and midline shift. With a radiological diagnosis of supratentorial primitive neuroectodermal tumour, he underwent subtotal resection of tumour. The post-operative histopathology revealed diffuse large B cell lymphoma (DLBCL). Systemic lymphoma workup was essentially normal. He received five cycles of chemoimmunotherapy with rituximab, high-dose methotrexate (HDMTX), vincristine and procarbazine and had complete radiological response (CR). This was followed by whole brain radiotherapy (WBRT) to a dose of 36 Gy in 20 fractions and sequential tumour bed boost to a dose of 9 Gy in 5 fractions by three-dimensional conformal technique. Subsequently, he received two cycles of consolidation chemotherapy with high-dose cytarabine. At completion of treatment, 3 and 6 months thereafter, MRI brain showed CR. At last follow-up visit, 13 months from the date of diagnosis, he was disease-free and asymptomatic with the exception of dimness of vision in both eyes due to long-standing bilateral optic atrophy.
CONCLUSION: This report highlights the fact that paediatric PCNSL may be effectively treated by a combination of HDMTX and rituximab-based chemoimmunotherapy followed by consolidation with conformal WBRT and tumour bed boost. Lack of awareness of this rare entity may lead to diagnostic delay and potential ramifications as exemplified by chronic atrophic papilloedema and visual loss in the illustrative case.