Primary CNS Lymphoma (PCNSL): Risk Factors, Symptoms, Diagnosis, and Treatment

Primary Central Nervous System Lymphoma (PCNSL) is a rare, aggressive non-Hodgkin lymphoma confined to the brain, spinal cord, leptomeninges, or eyes (intraocular lymphoma). It represents ~2–3% of primary brain tumors but is the most common primary brain malignancy in immunocompromised adults.

Risk Factors

• Immunodeficiency: HIV/AIDS (especially CD4 <100), post-transplant immunosuppression, congenital immunodeficiencies
• Age: Median diagnosis ~65 years (immunocompetent); ~35–45 years (HIV-associated)
• Sex: Male predominance (~1.5:1)
• Autoimmune conditions: Possibly increased risk (e.g., SLE, rheumatoid arthritis)

Symptoms (Depend on Tumor Location)

• Supratentorial brain: Headaches, seizures, focal deficits (weakness, aphasia), cognitive/personality changes
• Eyes (vitreoretinal): Floaters, blurred vision, decreased visual acuity
• Spinal cord/leptomeninges: Radiculopathy, bowel/bladder dysfunction, cranial nerve palsies
• Systemic: Fever, weight loss, night sweats (less common than in systemic lymphoma)

Diagnostic Workup

• MRI Brain/Spine: Characteristic homogeneous enhancing lesions, often periventricular; "ring-enhancing" pattern in immunocompromised patients
• Ophthalmologic exam: Slit-lamp examination, vitreous biopsy for ocular involvement
• Lumbar Puncture: CSF cytology, flow cytometry, IgH rearrangement, cytokines (IL-10 > IL-6 suggests PCNSL)
• Stereotactic Brain Biopsy: Definitive diagnosis; avoid corticosteroids beforehand (reduces diagnostic yield)

Treatment

High-dose methotrexate (HD-MTX) is the backbone of induction therapy (typically 3.5–8 g/m²). Regimens vary by immune status:

• Immunocompetent: HD-MTX + rituximab ± cytarabine ± thiotepa; consolidation with autologous stem cell transplant (ASCT) or whole-brain radiation (WBRT)
• Immunocompromised: Dose-adjusted chemotherapy; avoid WBRT if possible (neurotoxicity risk)
• Ocular involvement: Intravitreal methotrexate/rituximab + systemic therapy
• Relapsed/Refractory: Clinical trials, CAR-T, ibrutinib, lenalidomide, WBRT (if not previously irradiated)

Prognosis

• 5-year OS: ~60–70% (immunocompetent, modern regimens); lower in elderly/HIV
• Key prognostic factors: Age, performance status, LDH, CSF protein, deep brain involvement
• Late effects: Neurocognitive decline (especially post-WBRT), endocrine dysfunction, secondary malignancies

Specialized neuro-oncology/hematology centers optimize outcomes for this rare malignancy.