Bilateral Primary Central Nervous System’s Lymphoma of Cerebellopontine Angles: A Case Report

Abstract

Primary central nervous system lymphoma (PCNSL) mostly occurs in supratentorial regions. Our patient underwent surgery because of headaches and pain and sensorineural hearing loss in his right ear and bilateral extra axial CPA mass in MRI. Histopathology reveals diffuse large B-Cell lymphoma.

Introduction

Primary central nervous system lymphoma (PCNSL) is a rare form of non-Hodgkin’s lymphoma and does not exhibit systemic symptoms [1]. Most cases of PCNSL are supratentorial, involving the corpus callosum, basal ganglia, thalamus, and periventricular region [1]. Involvement in the infratentorial region is rare, occurring in only 10–20% of cases. PCNSL in the cerebellopontine angle (CPA) region is particularly very rare and may be misdiagnosed as other tumors such as schwannoma or meningioma. In this report, we present a unique case of PCNSL affecting both CPA areas.

Case Report

The patient is a 31-year-old man with headaches, dizziness, and pain in his right ear for 5 months. On the initial examination by an otolaryngologist, the external ear canal is suctioned with the diagnosis of wax impaction. Patient’s symptoms did not improve, and other symptoms occurred (hearing loss in the right ear, deviation of the mouth to the left, and difficulty swallowing). During the neurological examination, the Romberg test yielded negative results, and the cerebellar test appeared normal. Additionally, there was evidence of the patient’s swallowing disorder. In stimulation of posterior pharynx, palate elevated and deviated to the right side, but gag reflex presentation can reveal dysfunction of the 10th cranial nerve.

Magnetic resonance imaging (MRI) revealed the presence of a bilateral extra-axial CPA mass. The MRI showed hypointensity in T1-weighted and hyperintensity in T2-weighted. The MRI also indicated the presence of a mass in the bilateral internal auditory canal (IAC), measuring 5*10 mm on the right side and 13*6 mm on the left side, with extensions into the CPA (Fig. 1). A brain computed tomography (CT) scan displayed an isodense mass in the CPA with enlargement of the IAC, particularly on the right side.

Fig. 1.

MRI showed isointense bilateral CP angle mass in T1-weighted image (a) and hyperintensity mass with medial and inferior extension toward cranial nerve 10 in T2-weighted image (according to lower cut of MRI) (b). Bilateral internal auditory canal (IAC) enhancing mass with extensions to CPA was seen (c & d)

Preoperative audiometry revealed asymmetric bilateral sensorineural hearing loss, primarily affecting the right side. Also, speech reception threshold (SRT) was lower on the right side. The patient underwent right retrosigmoid craniectomy, with partial resection of visible tumor. After tumor exposure, an extra-axial lesion was seen with a soft texture which had entered the internal acoustic canal and near-total resection was obtained. Histopathologic examination revealed the presence of diffuse infiltrative intermediate to large mononuclear cells with vesicular chromatin, prominent nucleoli, frequent mitoses, and small areas of necrosis. These findings are consistent with brain lymphoma, most likely of the Diffuse large B cell type (DLBCL). An immunohistochemistry (IHC) study showed tumor cells were positive for CD45, CD20, CD79a, MUM1, BCL2, and ki67 (in approximately 60% of the tumor cells) (Fig. 2). The tumor cells were negative for cyclinD1, S100, CD30, CD3, and CD5. The primary diagnosis of DLBCL was confirmed. Based on this diagnosis, he referred to a radiation oncologist for further evaluation and treatment. In the whole-body assessment, no systemic involvement was found. Human immunodeficiency virus type 1 antibody was negative. A high-dose methotrexate (HD MTX) chemotherapy regimen was started for treatment, and continued for two courses. After the first session of chemotherapy, the patient’s hearing in their right ear and right facial paresis improved in examination (but not resolved completely). No remission was found in the follow-up MRI, after 6 months.

Fig. 2.

H&E, x200, x400: Diffuse infiltrate of intermediate to large mononuclear cells. These neoplastic B cells have vesicular chromatin and visible nucleoli (a & b). IHC, x200: CD20 strongly positive in majority of lymphocytes (c). IHC, x200: MUM1 positive in most lymphocytes (d)

Discussion

Multiple tumors involving the CPA region include cranial nerve tumors (schwannoma), meningioma, epidermoid cyst, metastasis and glomus jugular tumor [1]. PCNSL is a non-Hodgkin’s malignancy that originates in the craniospinal axis and is limited to the brain, leptomeninges, eye and spinal cord and does not have systemic symptoms [1]. Our patient is the third reported case of bilateral CPA lymphoma.

Involvement of CPA with PCNSL has been seen in the range of age from 21 to 82 years [2]. This tumor is more common in women and is seen more often on the left side, although cases of bilateral tumors have been reported. The most important PCNSL risk factor is acquired or congenital immunodeficiency. The average age of healthy people is 53 to 57 years and the male to female ratio is 1.2 to 1. The average age of immunocompromised people has decreased to 33 years and the ratio of males to females are 7.38 to 1 [3].

Symptoms are non-specific and an accurate diagnosis before surgery is based on histopathological results. Most of the related symptoms of CPA’s PCNSL include sensorineural hearing loss, headache, nausea, dizziness, and facial palsy, depending on the size of mass and anatomical structures around it. Tumors involving the CPA area can cause symptoms of trigeminal, facial, vestibulocochlear nerve involvement and dysfunction of the cerebellum (4, 2). Our patient presented with symptoms of bilateral asymmetric sensorineural hearing loss, headache and disorder in the right facial nerve.

It is commonly known that PCNSL is seen as a single intracranial and infiltrative mass, but it can also be in the form of multiple masses. Classically, periventricular lesion occurs in 20–40% of healthy people and 50% in immunocompromised people [2]. In the CT scan, the PCNSL lesion in the CPA region is hyperdense and homogenous after injection [3]. Bone destruction and widening of the inner ear canal are rare, which is different from acoustic neuroma. In MRI, it is homogenous iso in T1-weighted images and homogenous isointense to hyperintense in T2-weighted images and is accompanied by low edema around it [4].

Due to the rarity of this tumor and clinical symptoms similar to CPA tumors, it is very difficult to diagnose before surgery. Differential diagnoses of tumors in this area include schwannoma, meningioma, metastatic epidermoid cyst, and glomus jugular tumor. In Lal et al. study with 122 cases of CPA tumors, no lymphoma was reported among patients [5]. Imaging appearance of PCNSL in CT scan is hyperdense mass lesion. T2-weighted images on MRI can be specific for PCNSL tumors in the CPA region. The T2-weighted images are isointense to hypointense due to their high cellularity and the high ratio of nucleus to cytoplasm, and they have restrictive appearance in Diffusion-weighted imaging views (DWI) [2]. Differential diagnosis includes schwannoma, metastasis and less probably meningioma and epidermoid cyst based on MRI.

PCNLS treatment includes chemotherapy, radiotherapy and target molecular therapy. In patients with acute symptoms and large mass, surgery with decompression is one of the treatments [4]. There are no chemotherapy guidelines for the treatment of patients [4]. In patients with newly diagnosed PCNLS, the average survival time is 2 to 3 months without treatment [4].

Due to the adhesion of the lesion to the adjacent cranial nerves, complete resection of the mass was not possible. Also, in Awadhesh et al.‘s study, the mass was not completely resected, although he reported that the mass was completely separated from the cranial nerves [1]. In another study, a sample was taken from the lesion only for histological diagnosis [4]. Also, if there is a strong clinical suspicion and there are no contraindications for lumbar puncture (LP), sending a CSF sample for cytology can be used for diagnosis [6].

Conclusion

The CPA tumors are known to most neurosurgeons. But paying attention to uncommon differential diagnoses, including lymphoma, is important. Especially in cases where the imaging view is unusual, other diagnoses should be considered. Despite a low prevalence of PCNLS in cerebellopontine angle, lumbar puncture is recommended in strong clinical suspicion.

Author contributions

Conception of the work: Abdolhadi Daneshi, Omid Masoudi, Seyed Mohammad Reza Mohajeri. Data collection: Omid Masoudi, Seyed Mohammad Reza Mohajeri, Hossein Ghazvini, Saina Darvishnia. Data analysis and interpretation: Fatemeh Montazer, Arash Fattahi. Drafting the article: Omid Masoudi, Seyed Mohammad Reza Mohajeri. Critical revision of the article: Arash Fattahi. Other (study supervision, fundings, materials, etc): Abdolhadi Daneshi

Funding

No funds, grants, or other support was received.

Declarations

Ethics Approval and Consent to Participate

All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript. No funds, grants, or other support was received.

Consent to Participate

Informed consent was obtained from participant included in the study.

Conflict Interests

The authors declare that they have no conflict of interest. All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.