Primary central nervous system lymphoma – Presenting as a posterior fossa extradural mass lesion: A rare entity and literature review

Amit Singh; G Krishna Kumar; Shashi Sekhar Singh; Karamtoat Sugali Kiran; Bhavani Prasad Ganji

doi:10.4103/IJNO.IJNO_6_20

CASE REPORT

Year : 2020 | Volume : 3 | Issue : 1 | Page : 52-55

Primary central nervous system lymphoma – Presenting as a posterior fossa extradural mass lesion: A rare entity and literature review

Amit Singh, G Krishna Kumar, Shashi Sekhar Singh, Karamtoat Sugali Kiran, Bhavani Prasad Ganji
Department of Neurosurgery, Yashoda Hospitals, Secundrabad, Telangana, India

Date of Submission	07-May-2020
Date of Acceptance	04-Jun-2020
Date of Web Publication	2-Jul-2020

Correspondence Address:
Dr. Karamtoat Sugali Kiran
Department of Neurosurgery Yashoda Hospitals, Secundrabad, Telangana
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJNO.IJNO_6_20

Abstract

Primary central nervous system lymphoma (PCNSL) is an extranodal non-Hodgkin's lymphoma (NHL) confined to the brain, leptomeninges, eyes, or spinal cord. Primary NHL of the cranium with extra- and intracranial extension without systemic or skeletal manifestation in an immunocompetent patient is extremely rare. The prognosis of PCNSL is inferior to that of other NHL subtype. We describe a case of 49-year-old woman presented with occipital headache for 1 month, without any deficits. Imaging showed extradural mass lesion in the posterior fossa based at the trocula with minimal inner bony table changes mimicking primary bony tumor, meningioma, lymphoproliferative disorder, or metastatic tumor. We operated upon this patient, and histopathology was suggestive of B-cell NHL. On further evaluation, there was no systemic involvement. The patient was planned for radiotherapy followed by six cycles of chemotherapy with rituximab and bendamustine. There are case reports of cranial vault lymphomas involving frontoparietal/temporal region. So far, no posterior fossa extradural lesion reported till now.

Keywords: Cranial vault lymphoma, extradural lymphoma, primary central nervous system lymphoma

How to cite this article:
Singh A, Kumar G K, Singh SS, Kiran KS, Ganji BP. Primary central nervous system lymphoma – Presenting as a posterior fossa extradural mass lesion: A rare entity and literature review. Int J Neurooncol 2020;3:52-5

How to cite this URL:
Singh A, Kumar G K, Singh SS, Kiran KS, Ganji BP. Primary central nervous system lymphoma – Presenting as a posterior fossa extradural mass lesion: A rare entity and literature review. Int J Neurooncol [serial online] 2020 [cited 2022 Jun 27];3:52-5. Available from: https://www.Internationaljneurooncology.com/text.asp?2020/3/1/52/288793

Introduction

Primary central nervous system lymphoma (PCNSL) is an extranodal non-Hodgkin's lymphoma (NHL) confined to the brain, leptomeninges, eyes, or spinal cord.^[1] PCNSL is a rare brain tumor and subtype of NHL. Approximately 90% of PCNSL cases are diffuse large B-cell lymphomas (DLBCLs), with the remainder consisting of T-cell lymphomas, poorly characterized low-grade lymphomas, or Burkitt's lymphomas.^[2] The primary NHL of the skull and cranial vault is extremely rare. The International PCNSL Collaborative Group has developed guidelines to determine the extent of disease.^[3] Till date, very few cases are reported in the literature for cranial vault lymphoma and mostly involve the frontoparietal and temporal regions.^[4],[5] We report the first case of posterior fossa extradural lymphoma, without any subcutaneous scalp swelling.

History

A 49-year-old female, without any comorbidities, immunocompetent, presented with complaints of occipital headache for 1 month, which is insidious in onset, gradually progressing, constant, and dull aching type of pain. On examination, the patient was neurologically intact. There was no evidence generalized lymphadenopathy or organomegaly.

Investigation

The patient underwent magnetic resonance imaging (MRI) of the brain, which showed a well-defined heterogeneous T2 iso- to hyperintense extra-axial mass lesion with few cystic areas seen at the level of trocula extending into the posterior fossa inferiorly and superiorly posterior to the occipital lobes. It measured 6.3 cm × 3.3 cm × 2.9 cm in dimensions and was seen displacing the cerebellar hemispheres, the tentorium, the torcula, and the transverse sinus anteriorly. There was mild thickening of the occipital bone with scalloping along its inner table with. Post contrast showed homogeneous and intense enhancement. MR venography showed good opacification and normal signal in the torcula, straight sinus, and left transverse sinus; right transverse sinus is hypoplastic. No evidence of intradural tumor invasion [Figure 1] and [Figure 2]. Positron-emission tomography–computed tomography (CT) was done; there was no evidence of tumor elsewhere in the body.

Figure 1: Magnetic resonance imaging of brain axial imaging of the patient showing. (a) T2 hyperintense extradural mass lesion with anterior displacement of the trocula, cerebellum, and occipital lobe. (b) T1 axial images showing hypo–isointense lesion. (c) Post gadolinium T1 axial contrast images showing intensely enhancing extradural lesion

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Figure 2: (a-c) Are the T2 sagittal images showing extradural hyperintense lesion with epicenter around trocula with superior and inferior extension of tumor. (d-f) Are the post contrast images

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Surgical procedure

The patient underwent occipital–suboccipital craniotomy in a prone position. The inner surface of the bone at the level of the trocula showed moth-eaten appearance with a peripheral thickening. Outer table and scalp were normal. An extradural mass was seen which was firm, nodular with few hard areas, and at some areas, the tumor was densely adherent to the underlying dura. Intraoperative frozen section was done, which was suggestive of lymphoma. In view of that and dural adhesion at the level of the trocula, subtotal removal was done. The disease part of the bone was removed.

Histopathology finding

Histopathologic examination showed fibrocollagenous fragments infiltrated by sheets of relatively monomorphic cells with scant cytoplasm and hyperchromatic nuclei. Mitosis is inconspicuous. There was no evidence of necrosis and apoptosis. These features are suggestive of low-grade B-cell NHL. On immunohistochemistry (IHC), tumor cells are diffusely positive for CD20, CD5, CD45, CD10, and Bcl2. Mib-1 index is around 10%–15%. Tumor cells are negative for EMA, S100, Cyclin D1, and CD138 [Figure 3] and [Figure 4].

Figure 3: Histopathology image showing sheets of atypical lmphoid cells with background fibrosis on H and E, stain

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Figure 4: Immunohistochemistry positive marker imgaes. (a)CD20, (b) CD45, (c) CD10, (d) CD5, (e) MIB index, and (f) bcl2

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Postoperative period

Postoperative course was uneventful, and the patient discharged after 4 days. The patient was planned for radiotherapy followed by six cycles of chemotherapy with rituximab and bendamustine. Follow-up MRI awaited after 3 months.

Discussion

The incidence of NHL is 3%–4% of all neoplasms in the general population. PCNSL incidence is around 2%. It rarely involves the immunocompetent patients. The incidence goes up to 20% in immunocompromised and posttransplant patients. These lesions are commonly reported in the sixth and seventh decades, whereas in immunocompromised, the median age is around 40 years.^[6],[7],[8] Our patient was immunocompetent and presented at 49 years.

We did a literature search in PubMed on extradural cranial lymphomas. We found 58 relevant case reports out of 107 results. Of 58 reports, only 2 were Burkitt lymphoma, and the rest were NHL. Around 86% of the patients presented with scalp swelling. Only 3 (5.2%) patients were immunocompromised. The frontal bone is the most commonly affected around 62%, followed by the parietal and temporal bones. Three patients had orbital involvement. Five percent of patients were <16 years. One patient had multiple cranial nerve palsy. Twelve patients had sinus thrombosis and 2 had clival involvement.

PCNSL most commonly presents as soft-tissue swelling of the scalp, followed by headache. Rarely presents as seizures, cranial nerve palsy and raised intracranial pressure. Orbital lymphomas present with vision loss. These tumor cells spread from the diploic spaces along the emissary vein to involve the pericranium and scalp to present as the scalp mass and also spread internally to involve the meninges.^{[9],[10],[11]} Our patient presented with headache without any scalp swelling probably and the lesion was restricted intracranially, probably due to ill-formed emissary veins.^[12]

MRI of the brain with contrast study is the investigation of choice for PCNSL. MR venography shows us the involvement of sinus and its displacement. CT can be done to look at the changes in the bone. The scalp mass is better visualized with MRI. The mass is typically iso- to hyperintense on T2 and homogeneously enhancing on post-contrast images. The differential diagnosis showed primary skull tumors, metastatic skull tumors, and intraosseous meningiomas.^[13]

Primary central nervous system DLBCLs is composed of centroblasts or immunoblasts clustered in the perivascular space, with reactive lymphocytes, macrophages, and activated microglial cells intermixed with the tumor cells. Most tumors express pan-B-cell markers, including CD5, CD10, CD19, and CD20. An intraoperative frozen section should be done if there is suspicion of PCNSL, and it may influence the extent of the surgical excision.^[14]

The management of PCNSL involves surgery/biopsy followed by radiotherapy and chemotherapy. In various case reports, they did a needle biopsy from the scalp mass; few did maximum safe resection of tumors followed by adjuvant therapy. Most commonly followed regimen for PCNSL is cyclophosphamide, adriamycin, vincristine, and prednisolone (CHOP).^[15] Our case was managed by the maximum safe excision of the tumor followed by radiation and eight cycles of chemotherapy (rituximab and bendamustine). On IHC, CD20 was positive; hence, we are treating with rituximab-based chemotherapy. The prognosis of extradural lymphoma is uncertain, whereas of PCNSL, 1-year survival of patients aged <65 years is around 60% and for more than 65 years is <50%.^[7],[16]

Conclusion

Although this condition is rare, NHL diagnosis must be considered in the differential diagnosis in any patient with MRI features suggestive of extradural posterior fossa mass lesion with bony changes. Aggressive therapy is required for these unusual cases. CD markers study must be performed to confirm the diagnosis as well as for monitoring prognosis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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