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Primary lymphoma in the brain is uncommon, accounting for only 2% of primary intracranial neoplasms,1 although its incidence seems to be dramatically increasing.2Leptomeningeal lymphomas are even rarer but have been described1 3 4; however, no leptomeningeal lymphoma of the follicular type has previously been reported. We present a case of a primary meningeal follicular lymphoma which mimicked a sphenoid wing meningioma, both radiologically and intraoperatively.
A 57 year old Ghanaian woman was referred with a 3 year history of worsening bitemporal headache, followed by a 6 month history of daily right frontal headache lasting for 2–3 hours associated with mild photophobia. There were no reports of seizures, nausea, or other visual disturbances. Her medical history was 3 years of treated hypertension, sickle cell carrier trait, and a cataract extraction. The patient was obese but physical examination was otherwise normal. Neurological examination showed no papilloedema and there were no cranial nerve or long tract signs.
Brain CT showed an enhancing mass consistent with a right sided sphenoid wing meningioma (figure A). Right pterional craniotomy was performed and a tumour located under and adherent to the overlying dura was identified. It was entirely extracerebral, measuring 6×4×6 cm, with the greyish colour and hard consistency typical of a meningioma. The tumour and the adherent, thickened dura was macroscopically completely removed.
Histologically the lesion consisted of lymphoid tissue with an ill defined follicular architecture (figure B). The follicles varied in size and shape and infiltrated the overlying dura. Follicular centres were composed of a mixture of centrocytes and centroblasts with frequent mitotic figures and apoptotic bodies (figure C). Immunohistochemical staining confirmed that these cells had a B lymphocytic phenotype (CD20 positive) with kappa light chain restriction. Staining for Bcl-2 protein, which is an inhibitor of apoptosis and is expressed in 90% of follicular lymphoma, was found to be positive. The histological appearances and immunohistochemical profile confirmed a follicular lymphoma.
The patient made an uneventful recovery and was referred for staging investigations and consideration of postoperative therapy. An LDH estimation was within normal limits and HIV serology was negative. Whole body CT including repeat CT of the brain did not show any evidence of lymphadenopathy or lymphomatous deposit. Bone marrow examination was declined. Postoperative adjuvant whole brain or localised radiotherapy was discussed with the patient, however, she declined any further intervention. She has been closely reviewed in the follow up clinic and after 6 months there has been no clinical or radiological evidence of relapse.
Primary intracerebral lymphomas represent about 2% of intracranial neoplasms and 2% of all lymphomas. They occur most commonly in the 6th decade of life with a female to male ratio of roughly 2:1.1 The association between primary intracranial lymphoma and immunodeficiency has long been established, and it is not surprising, therefore, that the incidence has increased 10-fold over the past 3 decades with the onset of transplant surgery and, particularly the AIDS epidemic.2 In postmortem studies, these neoplasms are found, on average, in 5.5% of AIDS cases, and malignant cerebral lymphoma is the most common diagnosis of a focal intracranial lesion in patients with AIDS.1 3 Malignant primary lymphoma can occur throughout the CNS and they often have a periventricular distribution. Multifocality seems to be more common in patients with AIDS. The CT scan usually shows hyperdense masses with peritumorous oedema and 92% enhance after administration of contrast medium.1
Leptomeningeal lymphoma is usually encountered as a late complication of systemic non-Hodgkin’s lymphoma, although primary leptomeningeal lymphoma is occasionally seen. The prognosis for these tumours is poor.4 Diffuse intracranial lymphomas have been mistaken for more common lesions: solitary primary B cell lymphoma of the cerebellopontine angle mimicking acoustic neurilemoma or meningioma has been reported5; Vigushin et al 6 reported a patient with a calcified temporoparietal lymphoplasmacytic lymphoma which resembled a meningioma; however, this tumour was entirely extradural. There is only one previous report of a follicular rather than diffuse intracranial lymphoma: Rubinstein7 described a case of follicular lymphoma metastasis found in the dura of a 61 year old man at necropsy.
We found no report of a primary follicular extracerebral lymphoma. Similar radiological and intraoperative appearances of the tumour in our case to sphenoid wing meningioma suggest that this entity should be considered as a rare differential diagnosis.
We thank Professor Francesco Scaravilli, National Hospital for Neurology and Neurosurgery and Dr Mark Napier, The Meyerstein Institute of Oncology, Middlesex Hospital, for their help with this report.
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