MR Findings of Primary Choroid Plexus Papilloma of the Cerebellopontine Angle: Report of Three Cases and Literature Reviews

Pearls and Pitfalls of Imaging in Pediatric Brain Tumors

The central nervous system (CNS) tumors constitute the most common type of solid tumors in the pediatric population. The cerebral and cerebellar parenchyma are the most common site of pediatric CNS neoplasms. Imaging plays an important role in detection, characterization, staging and prognostication of brain tumors. The focus of the current article is pediatric brain tumor imaging with emphasis on pearls and pitfalls of conventional and advanced imaging in various pediatric brain tumor subtypes. The article also elucidates changes in brain tumor terms and entities as applicable to pediatric patients, updated as per World Health Organization (WHO) 2016 classification of primary CNS tumors. This classification introduced the genetic and/or molecular information of primary CNS neoplasms as part of comprehensive tumor pathology report in the routine clinical workflow. The concepts from 2016 classification have been further refined based on current research, by the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy (cIMPACT-NOW) group and published in the form of updates. The updates serve as guidelines in the time interval between WHO updates and expect to be broadly adopted in the subsequent WHO classification. The current review covers most pediatric brain tumors except pituitary tumors, meningeal origin tumors, nerve sheath tumors and CNS lymphoma/leukemia.

Cerebello-pontine and Cerebello-medullary Fissure Choroid Plexus Papilloma in a Child - Case Report and Review of Literature

Choroid plexus papillomas (CPP) are commonly seen in the supratentorial compartment in children and only very rarely in the posterior fossa. CPP in the cerebello-pontine angle and cerebello-medullary fissure (CPA) in the pediatric age group are extremely rare with only seven previous cases reported in literature. The authors present the case of a 7-year-old girl who presented with neck tilt, imbalance, and headache. The MRI showed a lesion with a frond-like appearance in the CPA with heterogeneous enhancement. The tumor was excised radically using a cerebello-medullary fissure approach. The authors review and analyze the literature on this rare pediatric tumor, with specific attention to radiology and the surgical aspects.

Pediatric choroid plexus papilloma arising from the cerebellopontine angle: systematic review with illustrative case

INTRODUCTION

Choroid plexus tumors are uncommon intraventricular tumors that develop from the choroid plexus of the central nervous system. Choroid plexus papillomas arising from the cerebellopontine angle have been reported to almost exclusively occur in adults and are rarely found in children.

METHODS

We report a systematic review conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines of SCOPUS and PubMed databases for case reports and case series of choroid plexus papillomas arising in the cerebellopontine angle in the pediatric population and discuss clinical presentation, imaging features, management options, and outcomes. We also report a case managed at our center.

RESULTS

Ten cases of pediatric choroid plexus papillomas arising in the cerebellopontine angle were identified from the systematic review in addition to the case reported here, resulting in a total of eleven cases. The patients' median age was 8 years with a slight female sex predilection (1.2:1). Patients most commonly presented with headache, cerebellar signs, and cranial nerve palsies with median duration of symptoms at 4 months. All patients underwent surgical treatment with majority achieving gross total excision. No deaths were reported at median follow-up of 12 months. Complete neurologic recovery was attained in seven cases while partial recovery was seen in two cases.

CONCLUSION

Choroid plexus papillomas found in the cerebellopontine angle in the pediatric population are extremely rare but they should be considered in the differential diagnosis. Complete surgical resection is the mainstay of treatment with excellent outcomes achievable in majority of patients.

Uncommon low-grade brain tumors

The 2016 World Health Organization (WHO) classification of primary central nervous system (CNS) tumors includes numerous uncommon (representing ≤1% of tumors) low-grade (grades I-II) brain neoplasms with varying clinical behaviors and outcomes. Generally, gross tumor or maximal safe resection is the primary treatment. Adjuvant treatments, though their exact role is unknown, may be considered individually based on pathological subtypes and a proper assessment of risks and benefits. Targetable mutations such as BRAF (proto-oncogene B-Raf), TRAIL (tumor necrosis factor apoptosis inducing ligand), and PDGFR (platelet derived growth factor receptor) have promising roles in future management.

Choroid Plexus Papillomas of the Cerebellopontine Angle

OBJECTIVE

Choroid plexus papillomas (CPPs) of the cerebellopontine angle (CPA) are extremely rare. We present a series of 21 cases operated on in the last 7 years at our institution.

METHODS

During the period from January 2008 to October 2015, we encountered 102 histologically established cases of CPPs, of which 21 were located in the CPA region. Clinical profiles, radiologic features, surgical procedures, intraoperative findings, and outcomes were extracted from the patient records and neuroimaging data.

RESULTS

The 21 CPPs in the CPA region accounted for 20.5% of all CPPs. Two of the tumors occurred in pediatric patients. Tumor size was 2.5-4.7 cm. The rate of calcification was higher in the CPPs in the CPA region. Peritumoral cysts and cysts with small nodules were observed in our cases. A far lateral suboccipital approach was chosen for CPPs protruding inferiorly into the foramen magnum region (n = 14), and a suboccipital retrosigmoid approach was chosen for the other tumors. Total resection was achieved in 18 patients, and subtotal resection was achieved in 3 patients. During the follow-up period, only 1 patient experienced recurrence 32 months after the first operation. The recurrence turned out to be an atypical CPP.

CONCLUSIONS

CPPs in the CPA region cannot be easily differentiated from other tumors preoperatively. Cysts and calcifications appear on neuroimaging. CPPs in the CPA region usually protrude inferiorly into the foramen magnum region. As much tumor should be removed as possible to avoid recurrence and malignant transition.