Primary intraventricular central nervous system lymphoma in an immunocompetent patient.

We report a young 15-year-old boy with 6 months history of headache, vomiting, and seizure. He underwent septostomy followed by right ventriculoperitoneal shunt for obstructive hydrocephalus and was managed with empirical antituberculosis treatment. Magnetic resonance imaging (MRI) revealed solid, nodular, enhancing masses in bilateral lateral ventricles and 4(th) ventricle. Surgical biopsy from 4(th) ventricular lesion confirmed a B-cell lymphoma. Staging evaluation with MRI positron emission tomography and bone marrow biopsy were normal suggesting an intraventricular primary central nervous system lymphoma.

Introduction

Lymphoma of the central nervous system (CNS) can present with a wide variety of clinical symptoms and imaging findings, which can be challenging for both the clinician as well as the radiologist. Primary CNS lymphoma (PCNSL) is a rare variant of extranodal non-Hodgkin's lymphoma and accounts for 1% of all primary brain tumors. Lesions of PCNSL are almost always found within the brain parenchyma and may be superficial (subpial) or deep-seated (sub ependymal). Intraventricular PCNSL is an extremely rare presentation of PCNSL with = 15 patients described in literature.

We present a patient with PCNSL with lesions in bilateral lateral ventricle and in the 4th ventricle.

Case Report

A young 15-year-old boy had a 6 months history of continuous headache, recurrent vomiting, and a single episode of generalized tonic-clonic seizure. Magnetic resonance imaging (MRI) brain initially within 1 month of onset revealed asymmetrical dilation of bilateral lateral ventricles (L > R) for which endoscopic septostomy was performed at another hospital. The patient showed initial improvement for 2–3 weeks followed by recurrence of symptoms of headache and vomiting. Cerebrospinal fluid examination revealed mild pleocytosis with mildly elevated protein, normal sugar, negative acid-fast Bacilli, fungal cultures, and serology. Right ventriculoperitoneal shunt was performed and empirical antitubercular therapy was initiated at this hospital. The patient remained symptomatic with repeated bouts of headache and recurrent vomiting, despite repeated adjustments of shunt pressures by repeated reprogramming of shunt. Repeat MRI brain [Figure 1] revealed focal, nodular, well defined solid enhancing lesions in the right lateral ventricle and 4th ventricle. The patient had neurological decline with decline in sensorium, severe truncal ataxia, dual incontinence, and right gaze palsy with right 7th infra nuclear and 9th and 10th nerve palsy. Posterior fossa craniotomy and decompression of tumor in the 4th ventricle was performed and biopsy revealed round to oval and monomorphic cells with scanty rim of eosinophilic cytoplasm with large and hyperchromatic nucleoli with irregular nuclear membrane. Few mitotic figures were present, and tumor cells are positive for leukocyte common antigen and CD20 and were negative for CD3, synaptophysin, and glial fibrillary acidic protein. The mib1 labeling index was very high (80%), suggestive of non-Hodgkin's lymphoma (diffuse large B-cell type) [Figure 2]. In view of biopsy, further staging was performed with positron emission tomography MRI whole body which revealed metabolically active lesions in 4th ventricle and discrete lesions in bilateral lateral ventricles with no other systemic fluorodeoxyglucose uptake, suggestive of PCNSL. Bone marrow biopsy was normal.

Figure 1

Original magnetic resonance imaging images. (a and b) Flair images showing right lateral ventricular and 4th ventricular hyperintense nodular lesions. (c-e) Contrast enhancing nodular lesions in right lateral ventricle and 4th ventricle

Figure 2

Original histopathology of 4th intraventricular tumor: (a) H and E staining revealed diffuse infiltration by sheets of atypical lymphoid cells. (b) The individual atypical lymphoid cells are moderately pleomorphic with round to oval hyperchromatic nuclei, inconspicuous nucleoli, and moderate amount of eosinophilic cytoplasm. Frequent mitosis is present. (c) Immunohistochemistry done for CD20 showed strong membranous positivity. (d) KI67/MIBI labeling index was very high (almost >80% positivity)

Discussion

CNS involvement in lymphoma can be secondary to a systemic lymphoma, which is the most common presentation. Alternatively, there can be isolated involvement of the CNS without any systemic lymphoma, which is the PCNSL variant. Secondary CNS lymphoma is almost always due to non-Hodgkin's lymphoma with spread to CNS which usually occurs after a median of 5–12 months after the primary diagnosis. Two-thirds of such secondary lymphoma infiltration occurs into the leptomeninges, subependymal, dural, or even cranial nerves and one-third present with CNS parenchymal infiltration.[1] PCNSL is a rare variant of extranodal non-Hodgkin's lymphoma and accounts for 1% of all primary brain tumors and is commonly a diffuse large B-cell type. PCNSL is usually associated with an immunodeficiency state, but may also be observed in immunocompetent individuals. As opposed to secondary CNS lymphoma, lesions of PCNSL are almost always found within the brain parenchyma and may be superficial (subpial) or deep-seated (sub ependymal).

PCNSL commonly presents within the brain parenchyma in superficial (subpial) or deep-seated (subependymal location). Intraventricular PCNSL is an extremely rare presentation with only few case reports.[2345678] Most of these case reports have described PCNSL occurrence in a single cerebral ventricle except the involvement of right lateral ventricle and 4th ventricle in one report,[9] which is also the presentation of our patient.

The imaging features of PCNSL are not characteristic and usually reveals hypo- or iso-intense lesions on T1-weighted MRI, iso- or hyper-intense lesions on T2-weighted images, and lesions show moderate to marked contrast enhancement with variable surrounding edema and hence, diagnosis is established only by a biopsy.[10]

Differential diagnosis for intraventricular CNS lesions includes central neurocytomas, meningiomas, ependymomas, choroid plexus papilloma, metastasis, neurocysticercosis, and rarely PCNSL. The role of imaging is in aiding to distinguish from other tumors seen in intraventricular location and the diagnosis of PCNSL is essentially based on biopsy and histopathological examination. It is important that primary B-cell lymphoma should be included in the list of differential diagnosis of intraventricular tumors. The standard treatment for PCNSL is biopsy followed by systemic chemotherapy or with intrathecal chemotherapy.[11] High-dose chemotherapy with autologous stem cell transplant may be utilized in patients with chemoresistance.[12]

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Conflicts of interest

There are no conflicts of interest