Presentation
Headache.
Patient Data
Within the vermis of the cerebellum is a relatively hyperdense mass, which enhances with contrast. It extends inferiorly on the right. Although it effaces the lower parts of the 4th ventricle there is only minimal if any enlargement of the lateral ventricles.
A mass involves the vermis and inferior aspects of the right cerebellar hemisphere. It demonstrates heterogeneous enhancement with components that appear solid, subependymal and even sulcal/pial. Particularly, the inferolateral component demonstrates very low ADC values.
Case Discussion
The patient actually had a known diagnosis of treated follicular lymphoma approximately 10 years ago. Recently developed B symptoms and a rapidly enlarging left femoral node.
They went on to have a cerebellar biopsy.
Histology
The sections show cerebellar tissue extensively infiltrated by tumor, which extends also into the subarachnoid plane. Tumor consists of sheets of large cells, with moderate amounts of amphophilic cytoplasm. Nuclei are large and generally polygonal but moderately pleomorphic, with granular nucleoplasm and sometimes with fairly large nucleoli. Mitotic figures are frequent as are apoptotic tumor cells. The tumor cells show a tendency to surround and infiltrate the walls of blood vessels. The features are those of a non-Hodgkin large cell lymphoma and the tumor will be further characterized with immunohistochemical stains.
Immunohistochemical stains have been done. The tumor cells show strong staining for CD20, establishing that they are B cells. The Ki-67 antibody shows staining of >95% of tumor cells.
Final diagnosis
Diffuse non-Hodgkin large B-cell lymphoma, with a very high proliferative index
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