A 56 year-old female presented with a five months history of dizziness, focal motor seizures and progressive immobility. Past medical history revealed a transient ishemic attack four years previously. On examination she was agitated but had no focal neurological deficit. CT scan showed a large right frontal tumor with strong contrast enhancement and dural tailing effect, suggestive of a meningioma (Figure 1). There was moderate edema present in the surrounding brain parenchyma with mild dilation of the lateral ventricles. She underwent right frontal craniotomy and complete resection of the tumor. At operation, a hemorrhagic purple-colored tumor was found firmly adherent to the dura compressing the medial aspect of the right frontal lobe. The tumor appeared to be arising from the cribriform plate.
GROSS AND MICROSCOPIC DESCRIPTION:
The biopsy specimen was composed of several large pieces of grayish tissue with focal pink areas attached to a few dural fragments. The largest pieces measured 3-5 cm in diameter.
The tumor revealed sheets of heterogeneous lymphoid cells infiltrating the dural collagen with ill-defined follicular formations (Figure 2). Majority of the lymphoid cells were small in size consisting predominantly of centrocyte-like cells characterized by vesicular nuclei, irregular or folded nuclear membrane and sometimes with moderate amount of cytoplasm (Figure 3). Some immature follicle-like structures were present and surrounded by tumor cells (Figure 4). In many areas numerous plasmacytoid and plasma cells were seen (Figure 5). Although the tumor revealed occasional mitotic figures, no significant mitotic activity was present. Leptomeningeal cells were absent.
On immunohistochemistry, the small centrocyte-like cells were positive with CD20 (Figure 6). There were many interspersed reactive T cells by CD45RO (Figure 7). The light chain expression, especially in plasma cells, was restricted to kappa chain (Figure 8).
Postoperatively the patient was investigated for possible systemic disease. A CT scan of the abdomen and chest were normal. Laboratory examinations, including peripheral blood count, plasma immunoglobulins, serum electrophoresis and bone marrow biopsy, were all normal. The patient is symptom-free 18 months after a complete tumor resection.