Presentation
Unsteady gait and diplopia. The patient has a known history of systemic lymphoma treated 3 years ago.
Patient Data
MRI Brain shows an enhancing soft tissue mass in the region of the fourth ventricle with local mass effect without causing hydrocephalus. There is also a similar mass in the left caudothalamic groove.
MICROSCOPIC DESCRIPTION: 5,6,8. Paraffin sections show fragments of leptomeninges in specimens 5 and 6 and leptomeninges and cerebellar cortex in specimen 8. In each specimen there is a population of small to intermediate sized lymphocytes which show strong membrane staining for CD20. These are seen to infiltrate leptomeningeal connective tissue, aggregate around blood vessels and extend into blood vessel walls. Extension of these cells into cerebellar cortex is seen in specimen 8. No viral inclusions or fungal or bacterial organisms are identified. There are no granulomas. The features are strongly suggestive of B cell lymphoma.
DIAGNOSIS: Brain lesion: Lymphocytic infiltrate strongly suggestive of B cell lymphoma in leptomeninges and cerebellar cortex
Case Discussion
This patient has a previous history of a systemic B cell lymphoma treated with chemotherapy. After biopsy confirmation of the cerebellar lesion, the patient was referred back to his hematologist for further systemic investigation and treatment.
Secondary CNS lymphoma is typically a non-Hodgkin lymphoma and, unlike primary CNS lymphoma it more commonly involves the leptomeninges and is uncommonly detectable on CT/MR, with malignant cells found of CSF aspiration.