Presentation
Convulsions and personality changes.
Patient Data
Left frontal cortical gyral space-occupying lesion of abnormal signal. It elicits low signal on T1 and isointense signal on T2 and FLAIR to cortex. It shows high signal on DWI with matching low ADC values consistent with true diffusion restriction and homogeneous post-contrast enhancement T1 C+. It's surrounded by extensive vasogenic oedema which exerts a significant mass effect in the form of compression of the left lateral ventricle and mild midline shift.
Conclusion:
The lesion demonstrates strikingly low diffusion and vivid homogeneous contrast enhancement fairly typical of lymphoma. Other aetiologies (e.g. oligodendroglioma or metastasis) are less likely.
FDG avid left frontal lesion with SUV max 4 surrounded by a large photopenic vasogenic oedema. The lesion appears hyperdense on non contrast CT study.
No other hypermetabolic lesions were distinctive for neoplasia.
The patient went on to have a biopsy.
Histology
Serial sections examined revealed pieces of unremarkable brain tissue, together with pieces of tissue showing diffuse infiltrate formed of perivascular groups and scattered forms of medium-sized and large anaplastic cells with pleomorphic nuclei, occasional prominent nuclei, and frequent mitosis. The background shows lymphocytes and histocytes.
Immunophenotyping
CD20 is diffusely positive in cells.
Final diagnosis
Undifferentiated malignant round cell infiltrate onsistent with diffuse large B cell lymphoma.
Case Discussion
Primary CNS lymphoma is usually located in the periventricular subependymal regions.
In this case, the atypical location of the lesion (being cortical in location) made it hard to distinguish it from other neoplastic lesions such as gliomas/oligodendrogliomas or metastasis.
Atypical forms of primary CNS lymphoma include:
- primary dural lymphoma ( mucosa-associated lymphoid tissue (MALT),
- T‑cell lymphoma ( angiocentric pattern),
- lymphomatosis cerebri
- intravascular lymphoma
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