General
- Lymphomatoid granulomatosis is an angiocentric and angiodestructive lymphoproliferative disorder.
- It is characterised by polymorphous lymphoid infiltrates composed of EBV-positive atypical B cells within a T cell-rich inflammatory background
Definition
- Essential:
- Morphology of an intracerebral polymorphous lymphoid infiltrate with atypical EBV+, CD20+, CD30+/-, CD15- large neoplastic B cells of variable numbers.
- Blood vessel destruction.
Numbers
- It is a rare disease.
- Affects the brain in 26% of cases
- It usually manifests in adults in the fifth to sixth decade.
- A male predilection has been reported.
WHO Grade
- Grading depends on the proportion of EBV-expressing CD20+ B cells.
- The disorder is typically graded from 1 to 3, based on the number of EBV-positive lymphoid cells found.
- Most cases affecting the CNS correspond to grade 3, which should be classified as EBV+ diffuse large B-cell lymphoma of the CNS
Localisation
- The brain is affected in 26% of patients.
- CNS may be the only part of the body affected by post-transplant lymphoproliferative disorder, although CNS involvement is not frequent.
Histopathology Features
Macroscopic Features
- Lesions may resemble tumour or infarct-like areas of necrosis.
Microscopic Features
- Characterized by angiocentric and angiodestructive lymphoid infiltrates.
- Lesions consist of polymorphous lymphoid infiltrates, including CD4+ and CD8+ T lymphocytes, plasma cells, and atypical EBV+, CD20+ neoplastic B cells
- The infiltrates invade blood vessel walls, frequently inducing infarct-like necrosis of tumour and/or brain tissue.
- Grade 3 is characterized by large atypical B cells or aggregates numbering greater than 400 cells/mm2 (or > 50 cells/HPF)
Immunophenotype
- Neoplastic B cells are typically EBV+, CD20+, CD30+/-, and CD15-
- EBV presence is confirmed by EBER (EBV-encoded small RNA) staining
Pathogenesis
- It is an EBV-driven disease.
- The disease is hypothesised to result from defective immunosurveillance of EBV and an abnormal immune response towards $\text{EBV}$.
- Immunodeficiency generally increases the risk of lymphomatoid granulomatosis.
Clinical Features
- Focal neurological symptoms, headache, and/or cognitive impairment.
- The presentation may be indistinct from systemic manifestation.
Radiological Features
- MRI may reveal mass lesions throughout the CNS.
- Multiple punctate lesions along perivascular and periventricular spaces have also been reported on MRI.
Management
- Treatment is based on the histological grade.
- Since most CNS cases correspond to diffuse large B-cell lymphoma of the CNS, treatment options include corticosteroids, radiation, or chemotherapy.
Prognosis
- Lymphomatoid granulomatosis of the CNS usually follows an aggressive course.
- The unfavourable prognosis is due to most CNS biopsies corresponding to EBV-positive diffuse large B-cell lymphoma of the CNS.
- Clinical courses and treatment responses are generally unclear.
Made with Bullet