Atypical Choroid Plexus Papilloma of the Foramen Luschka in an Adult: A Case Report and Literature Review

Abstract

Choroid plexus papillomas are rare tumors of the central nervous system. They are mostly observed during childhood and are commonly located in the lateral ventricles. In adults, they are very rare and usually located in the fourth ventricle. We herein present a case of atypical choroid plexus papilloma of the foramen of Luschka in an adult. A 26-year-old male patient was presented with headache, dizziness, visual loss, and gait disturbance. Cranial imaging revealed a giant mass located in the foramen of Luschka with non-intense homogeneous contrast enhancement. Gross total removal of the tumor was achieved via the left telovelar approach. Transient swallowing difficulty and worsening of the nystagmus were observed in the early postoperative period. The patient was free of symptoms for 3 months postoperatively. The pathological examination yielded a diagnosis of atypical choroid plexus papilloma. We aimed to discuss the clinical findings and surgical treatment of the case.

Resumo

Os papilomas do plexo coroide são tumores raros do sistema nervoso central. Eles são observados principalmente durante a infância e são comumente localizados nos ventrículos laterais. Em adultos, eles são muito raros e geralmente localizados no quarto ventrículo. Apresentamos aqui um caso de papiloma atípico do plexo coroide do forame de Luschka em um adulto. Um paciente do sexo masculino de 26 anos apresentou dor de cabeça, tontura, perda visual e distúrbio da marcha. A imagem craniana revelou uma massa gigante localizada no forame de Luschka com realce homogêneo não intenso pelo contraste. A remoção total bruta do tumor foi obtida pela abordagem telovelar esquerda. Dificuldade transitória de deglutição e piora do nistagmo foram observadas no período pós-operatório inicial. O paciente ficou livre de sintomas por 3 meses no pós-operatório. O exame patológico produziu um diagnóstico de papiloma atípico do plexo coroide. Nosso objetivo foi discutir os achados clínicos e o tratamento cirúrgico do caso.

Keywords

atypical choroid plexus papilloma - foramen of Luschka - telovelar approach

Palavras-chave

papiloma atípico do plexo coroide - forame de Luschka - abordagem telovelar

Introduction

Choroid plexus papillomas are rare tumors of the central nervous system. They are mostly observed during childhood and commonly located in the lateral ventricles. In adults, they are much rarer and often located in the fourth ventricle. Although these tumors are usually located in the ventricles, in very rare cases they can be located in the parenchyma, foramina of Luschka, and cerebellopontine angle.[1] [2] The 2021 World Health Organization (WHO) Classification of Tumors of the Central Nervous System classifies choroid plexus tumors as papillomas (grade 1), atypical tumors (grade 2), and carcinomas (grade 3), according to number of mitotic figures.[3] [4]

The microscopic appearance of atypical choroid plexus papilloma is like that of typical choroid plexus papilloma, but the number of mitoses is 2 to 5 per 10 high-power fields.[5] Atypical choroid plexus papilloma is very rare in adults. We herein report a giant, atypical, and very rare condition. In addition, the surgical treatment of these tumors involves difficulties due to tumor size and location. In the current report, we aim to discuss the clinical findings and surgical treatment of the case.

Case

A 26-year-old male patient was evaluated for headache, dizziness, visual loss, and gait disturbance. He presented decreased visual acuity, horizontal nystagmus in the left eye, ataxia, and dysarthria, along with an impaired cerebellar examination. Papilledema was present in the fundus examination. A cranial magnetic resonance imaging (MRI) scan revealed a giant mass located in the left foramen of Luschka, extending from the cerebellopontine angle to the foramen magnum, involving the walls of the fourth ventricle and causing direct compression on the brainstem. The mass was hypointense on T1-weighted MRI scans, hyperintense on T2-weighted images, and it presented non-intense homogeneous contrast enhancement. The fourth ventricle was compressed, resulting in non-communicating hydrocephalus ([Fig. 1]).

Fig. 1 (A) T1-weighted coronal magnietic resosnance imaging (MRI) scan showing the tumor invading down the foramen magnum. (B) T1-weighted contrast-enhanced sagittal image showing a giant tumor seated on a large dural base. (C) Fluid-attenuated inversion recovery-weighted contrast-enhanced axial section image showing fourth ventricular compression. (D–F) Control-enhanced MRI scan performed 6 months postoperatively, surgical trace from which the tumor was removed in the coronal section, no residual tumor or recurrence is observed.

The patient was operated in the prone position. Following the midline incision, a predominantly left-sided suboccipital craniectomy was performed. The left cerebellar tonsil extending to the foramen magnum was retracted upwards, and the tumor was revealed. Then, the borders of the tumor were visualized through a left telovelar approach. The tumor had partially invaded the fourth ventricle wall, middle cerebellar peduncle, and pons. The lower cranial nerves were also partially surrounded by the tumor and pushed out of their anatomical courses. The tumor tissue was dissected very carefully with the help of an ultrasonic aspirator, since the borders could not be clearly distinguished. The part of the tumor extending to the anterosuperior border of the foramen of Luschka was removed with preservation of the basilar artery and its branches, as well as the seventh and eighth cranial nerves. Then, through a left telovalar approach, gross total removal of the tumor was performed.

No additional neurological deficit was observed in the early postoperative period, except for worsening of nystagmus of the left eye. On the third postoperative day, the patient developed difficulty in swallowing. No postoperative bleeding or significant ischemia was observed in the imaging scans. The patient's oral intake was stopped for a few days, and he was put on steroids and antiedema agents, which gradually improved the swallowing difficulty. The result of the pathological examination was atypical choroid plexus papilloma, WHO grade 2 ([Fig. 2]). At the follow-up after 3 months, the patient's vision had completely improved, and he had no nystagmus. The headache and vertigo complaints had improved, there was no gait disturbance, and the cerebellar examination was normal. The swallowing difficulty was completely resolved, and the patient was able to ingest liquid and solid foods without difficulty. A follow-up MRI scan showed no signs of any residual or recurrent tumor.

Fig. 2 (A) Photographs showing a papillary structure with a layer of columnar epithelial cells and fibrovascular stroma (hematoxylin and eosin stain, 100x magnification). (B) S100 immunoreactivity (200x magnification).

Discussion

Atypical choroid plexus papillomas are very rare in adults and usually located in the ventricles. Moreover, choroid plexus tumors can be observed very rarely in the foramen of Luschka. These factors make the differential diagnosis difficult. The foramen of Luschka is more commonly known as a passage through which ventricular tumors enlarge and extend into the extraventricular space. This is quite typical, especially for ependymomas.[6] In the case herein reported, although the tumor invaded the wall of the fourth ventricle, there was no significant mass in the ventricle. The tumor had extended anteriorly to the subarachnoidal space and based on the radiological findings, the differential diagnoses of expenditures of ependymoma and medulloblastoma were difficult. Vestibular schwannoma was also considered in the differential diagnosis due to its proximity to the internal acoustic canal and the seventh and eighth cranial nerves. However, vestibular schwannomas are extra-axial lesions that enlarge by pushing the cerebellar tissue instead of infiltrating it, and their borders are usually clearly defined. In addition, the tumor extended anteriorly into the subarachnoid space and showed proximity to the petroclival dura mater with a broad base. Therefore, it was like meningiomas in this location. Unlike meningiomas, contrast-enhanced MRI scans did not show dural thickening and dural tail in the case herein reported. Rarely, glial tumors, metastases, epidermoid cyst, and paraganglioma can also be observed in the foramen of Luschka and should be considered in the differential diagnosis.[7]

Due to the anatomical extension of the foramen of Luschka, tumors in this location may lead to findings related to the pons, medulla, cranial nerves, and cerebellum, and they may also cause hydrocephalus. In the case herein reported, there were complaints of vertigo, tinnitus, headache, and nausea/vomiting symptoms, along with difficulty in walking and speaking, as well as decreased visual acuity. There were dysmetria and dysdiadochokinesia on the left side. Moreover, the presence of horizontal nystagmus in the left eye was remarkable in the present case. The patient's nystagmus was not position-related, non-rotatory, and there was no ophthalmoplegia on the eye examination. The eye movements were normal. The severity of nystagmus in the left eye increased postoperatively. Unilateral horizontal nystagmus that is not accompanied by ophthalmoplegia and not positional is a very extreme condition. Middle cerebellar peduncle or medial longitudinal fasciculus damage has been reported as a possible cause of nystagmus in a case with atypical choroid plexus papilloma located in the cerebellar peduncle.[8] In the case herein reported, the fact that horizontal nystagmus was not related to position, and the absence of a rotatory component or of any ophthalmoplegia accompanied by nystagmus suggest a unilateral partial lesion of the paramedian pontine reticular formation (PPRF) in the pons. It should be kept in mind that horizontal nystagmus may occur due to giant tumors located in the foramen of Luschka and/or after surgeries performed in this area, and the patient should be evaluated in this respect before and after the operation. The horizontal nystagmus of the patient, which worsened after surgery, was completely resolved at the follow-up after 3 months.

For tumors located in the foramen Luschka, different surgical approaches can be applied according to the size and growth direction of the tumor. The retrosigmoid suboccipital approach can be used for tumors with an anterosuperior location and enlarged in the cerebellopontine angle; subtonsillar approaches, for tumors located more posteroinferiorly; the transvermian approach, for tumors growing toward the fourth ventricle; and the transcerebellar approach, for large tumors.[2] [7] [9] Adib et al.[9] divided the choroid plexus papillomas located laterally to the brainstem into three types based on the line between the medulla oblongata and the pons. The tumor is defined as type 1 if it is located superiorly to the line; type 2, if it is located inferiorly to the line; and type 3, if it extends to both parts. Type-3 tumors are large and may extend from the cerebellopontine angle to the foramen magnum.[9] In the case herein reported, the tumor was compatible with type 3 according to this classification, and it extended from the cerebellopontine angle to the foramen magnum. Considering the location and size of the tumor, the telovelar approach was preferred to reach the medial, lateral, anterosuperior and foramen magnum of the foramen of Luschka, and the tumor was grossly removed.

For the treatment of the tumors which are closely adjacent to the foramen of Luschka, the anteroinferior cerebellar artery (AICA), the posteroinferior cerebellar artery (PICA), the seventh, eighth, and lower cranial nerves may be damaged during surgery, especially in cases of large tumors. In addition, atypical choroid plexus tumors may also invade the surrounding tissues, as in the case herein reported. Therefore, dissection of the tumor from the surrounding tissues, especially from the brainstem, involves difficulties and may lead to undesirable situations. In the present case, the horizontal nystagmus in the left eye intensified after the operation, and dysphagia developed 3 days postoperatively.

The treatment of atypical choroid plexus tumors is surgical total resection. The role of adjuvant chemotherapy and radiotherapy in the treatment of these tumors is controversial. However, due to the localization and size of the tumor, adjuvant chemotherapy and radiotherapy are recommended in cases in which the tumor cannot be completely removed, or it has recurred.[4] [10] In the case herein reported, the tumor was grossly removed. Therefore, adjuvant chemotherapy and radiotherapy were not administered considering possible side effects and discussions on treatment efficacy. Frequent follow-up was recommended for possible recurrence and metastasis.

Conclusion

Although rare, atypical choroid plexus papilloma should be considered in the differential diagnosis of tumors located in the foramen of Luschka. Atypical choroid plexus papillomas present difficulties in surgery because they can invade the surrounding tissues. In cases of giant tumors extending from the pontocerebellar angle to the foramen magnum, the suboccipital telovelar approach provides the appropriate corridor for gross total removal.

Conflict of Interests

The authors have no conflict of interests to declare.

Informed consent

Informed consent was obtained from all the individuals included in the study.

Declaration of Patient Consent

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

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Publication History

Received: 03 May 2023

Accepted: 23 October 2024

Article published online:
27 March 2025