Pathology of choroid plexus papillomas: a review

Imaging of supratentorial intraventricular masses in children:a pictorial review- part 1

PURPOSE

This article is the first in a two-part series designed to provide a comprehensive overview of the range of supratentorial intraventricular masses observed in children. Our primary objective is to discuss the diverse types of intraventricular masses that originate not only from cells within the choroid plexus but also from other sources.

METHODS

In this article, we review relevant epidemiological data, the current genetics/molecular classification as outlined in the fifth edition of the World Health Organization's Classification of tumours of the Central Nervous System and noteworthy imaging findings. We conduct an exhaustive analysis of primary choroid plexus tumours as well as other conditions such as choroid plexus hyperplasia, choroid plexus cyst, choroid plexus xanthogranuloma, atypical teratoid rhabdoid tumour, meningioma, arteriovenous malformation and metastasis.

RESULTS

We comprehensively evaluated each supratentorial intraventricular mass, providing an in-depth analysis of their unique clinical and histological characteristics. The fifth edition of the World Health Organization Classification of Tumours of the Central Nervous System introduces major modifications. These important changes could potentially have a profound impact on the management strategies and subsequent outcomes of these tumours.

CONCLUSION

Intraventricular masses in children can arise from various sources. Surgical intervention is key for certain supratentorial intraventricular masses in paediatric patients, with preoperative neuroimaging essential to decide the best treatment approach, surgical or otherwise, as some cases may not require surgery.

Clinical, magnetic resonance imaging, and histological description of a choroid plexus papilloma with disseminated intraventricular and spinal cerebrospinal fluid drop metastases in a young adult dog: a case report

A 2-year-old male entire Cane Corso was presented for investigations into a 1-week history of ambulatory paraparesis and pelvic limb ataxia gradually deteriorating. Magnetic resonance imaging (MRI) revealed intraventricular space-occupying lesions affecting the fourth ventricle and lateral apertures and intradural-extramedullary space-occupying lesions at the level of C7 vertebra, L4-L5, and L7-S1 intervertebral disk spaces. Due to poor quality of life, the patient was euthanized. A post-mortem examination revealed partially encapsulated, multifocally infiltrative, and moderately cellular neoplastic masses. The histological description was similar for all masses. The cells appeared cuboidal with round central nuclei and a moderate amount of eosinophilic cytoplasm and were arranged almost exclusively in single-layered papilliform patterns supported by a fibrovascular stroma. Mitoses were rarely observed (1/2.37 mm2). The primary neoplasm was morphologically most consistent with a choroid plexus papilloma despite drop metastases. This is the first report of a histologically confirmed primary ventricular choroid plexus papilloma causing disseminated MRI-apparent intraventricular and spinal drop metastases.

Choroid plexus carcinoma with neuronal and glial differentiation in a 7-week-old male Sprague-Dawley rat

We describe a case of choroid plexus carcinoma arising in the cerebrum of a 7-week-old male Sprague-Dawley rat. The tumor mass occupied the right lateral ventricle of the cerebrum. Histological analyses revealed that the epithelial tumor cells had proliferated in tubular, cribriform, papillary and solid growth patterns in the vicinity of the choroid plexus, with slight invasion into the cerebrum parenchyma. We divided the tumor cells into cuboidal, elongated and intermediate cells. Immunohistochemical studies showed that these tumor cells expressed relatively high levels of cytokeratin AE1/AE3, vimentin and glial fibrillary acidic proteins, and low levels of nestin, oligodendrocyte transcription factor and doublecortin proteins. The present case was diagnosed as a choroid plexus carcinoma with neuronal and glial differentiation.

Magnetic Resonance Imaging and Clinical Findings Associated with Choroid Plexus Spinal Cord "Drop" Metastases

A 5 yr old castrated male whippet presented with a unique presentation of ambulatory paraparesis and subsequent diagnosis of primary intracranial choroid plexus carcinoma, with metastases to the cervical, thoracic, lumbar, and sacral spinal cord segments. Magnetic resonance imaging was performed initially of the thoracolumbar vertebral column and was followed by MRI sequences of the brain for confirmation of the presence of a primary intracranial tumor. The dog was euthanized immediately following diagnostic imaging due to the severity of clinical signs and poor prognosis. Postmortem examination confirmed the presence of a primary choroid plexus carcinoma, with diffuse metastatic lesions to the spinal cord. To the authors' knowledge, this is the first description of MRI findings of spinal cord metastasis of a choroid plexus carcinoma in a dog. Additionally, this case demonstrates primary clinical signs arising from metastatic lesions. This confirms the importance of extensive neuroimaging investigations when suspecting choroid plexus tumors and evaluating response to treatment regimens.

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.

The choroid plexus: a comprehensive review of its history, anatomy, function, histology, embryology, and surgical considerations

INTRODUCTION

The role of the choroid plexus in cerebrospinal fluid production has been identified for more than a century. Over the years, more intensive studies of this structure has lead to a better understanding of the functions, including brain immunity, protection, absorption, and many others. Here, we review the macro- and microanatomical structure of the choroid plexus in addition to its function and embryology.

METHOD

The literature was searched for articles and textbooks for data related to the history, anatomy, physiology, histology, embryology, potential functions, and surgical implications of the choroid plexus. All were gathered and summarized comprehensively.

CONCLUSION

We summarize the literature regarding the choroid plexus and its surgical implications.

Choroid plexus tumors: A clinico-pathological and neuro-radiological study of 23 cases

BACKGROUND

Choroid plexus tumors are intraventricular tumors derived from choroid plexus epithelium.

AIM

To study the choroid plexus tumors with reference to their clinical, radiological, and pathological features.

MATERIALS AND METHODS

The study was performed by the retrospectively reviewing the clinical, radiological, and pathological records of patients of choroid plexus tumors.

RESULTS

A total of 23 cases (11 males, 13 females) of choroid plexus tumor were diagnosed from 1997 to 2009. Fourteen patients were below 15 years of age. Raised intracranial pressure was the main presenting feature in all the cases. Tumor was located in lateral ventricle (n = 14; in 3 cases tumor was going into third ventricle), fourth ventricle (n = 7), and cerebellopontine angle (n = 2). Total tumor excision was achieved in 21 cases. The histopathology was suggestive of choroid plexus papilloma (n = 19), atypical choroid plexus papilloma (n = 1), and choroid plexus carcinoma (n = 2). Clears cell areas were noted in three cases. Other histopathological features observed were foci of calcification (n = 5), Psammoma bodies (n = 2), hemorrhage (n = 5), hyalinization (n = 2), and oncocytic changes (n = 1).

CONCLUSIONS

Choroid plexus tumors are intraventricular tumors arising from choroid plexus epithelium. The predominant clinical presentation is raised intracranial pressure. Surgery is the mainstay of treatment; histopathologically, they include choroid plexus papilloma, atypical choroid plexus papilloma, and choroid plexus carcinoma.

Choroid plexus papillomas: advances in molecular biology and understanding of tumorigenesis

Choroid plexus papillomas are rare, benign tumors originating from the choroid plexus. Although generally found within the ventricular system, they can arise ectopically in the brain parenchyma or disseminate throughout the neuraxis. We sought to review recent advances in our understanding of the molecular biology and oncogenic pathways associated with this disease. A comprehensive PubMed literature review was conducted to identify manuscripts discussing the clinical, molecular, and genetic features of choroid plexus papillomas. Articles concerning diagnosis, treatment, and long-term patient outcomes were also reviewed. The introduction of atypical choroid plexus papilloma as a distinct entity has increased the need for accurate histopathologic diagnosis. Advances in immunohistochemical staining have improved our ability to differentiate choroid plexus papillomas from other intracranial tumors or metastatic lesions using combinations of key markers and mitotic indices. Recent findings have implicated Notch3 signaling, the transcription factor TWIST1, platelet-derived growth factor receptor, and the tumor necrosis factor-related apoptosis-inducing ligand pathway in choroid plexus papilloma tumorigenesis. A combination of commonly occurring chromosomal duplications and deletions has also been identified. Surgical resection remains the standard of care, although chemotherapy and radiotherapy may be considered for recurrent or metastatic lesions. While generally considered benign, these tumors possess a complex biology that sheds insight into other choroid plexus tumors, particularly malignant choroid plexus carcinomas. Improving our understanding of the molecular biology, genetics, and oncogenic pathways associated with this tumor will allow for the development of targeted therapies and improved outcomes for patients with this disease.

Unusual radiologic findings and pathologic growth patterns on choroid plexus papillomas

Objective

Choroid plexus papillomas (CPPs) are generally regarded as benign tumors with typical radiologic and pathologic findings. However, they sometimes have unusual findings. We have analyzed radiologic findings and pathologic growth patterns on CPPs.

Methods

The study group included 5 male and 5 female patients (age range, 3 months to 58 years : median, 29 years). The study group included 3 pediatric and 7 adult patients. All patients underwent surgery; 9 patients had a gross total resection and 1 patient had a subtotal resection. We analyzed the radiologic findings (location, size, mottle-like appearance, enhancement, calcifications, and hydrocephalus) and pathologic growth patterns (typical papillary, papillary and solid, and papillary and tubular).

Results

The median follow-up duration was 21.3 months (range, 4-47.8 months). There were no recurrences after initial treatment. All patients had benign CPPs. Pediatric CPPs were 3.2 cm masses (range, 2.7-4 cm) with homogeneous enhancement and a mottle-like appearance, which pathologically showed the papillary growth pattern. Hydrocephalus was present in all pediatric patients. Postoperatively, subdural hygroma had occurred in two patients. In adults, CPPs were located in the fourth ventricle in 6 patients and suprasellar area in 1 patient. The size varied from 0.5-4.2 cm. Hydrocephalus and calcifications occurred in 3 and 4 patients, respectively. Three patients showed the heterogeneous enhancement without a mottle-like appearance and pathologically showed combined papillary and solid growth in 2 patients and papillary and tubular growth in one. Postoperatively, two patients with large masses had injuries of the brainstem and underwent shunt procedures for aggravation of hydrocephalus.

Conclusion

CPPs may show unusual radiologic findings, which preoperatively give the difficulty to be differentiated from other tumors. CPPs with unusual radiologic findings showed the combined pathologic growth patterns.

Imaging tumors of the pediatric central nervous system

Primary tumors of the central nervous system (CNS) are the second most common neoplasms in children and the leading cause of death in this patient population. The primary objective of this article is to describe the most common pediatric brain tumors and to offer an overview of their respective imaging features, primarily on magnetic resonance imaging. Precise anatomic characterization is essential for developing an appropriate differential diagnosis. Once equipped with this critical information, physicians should be better able to make firm diagnoses, leading to improved disease management and patient outcomes in the setting of CNS tumors of childhood.

99mTc-sestamibi scan differentiates tumor from other contrast enhancing tissue in choroid plexus tumors

Choroid plexus tumors are rare brain tumors which account for 0.4% to 0.6% among brain tumors. Tumor resection is known to be of large prognostic impact, and re-resection of residual tumors is a part of standard care. However, after multiple resections it can become difficult to differentiate tumor from reactive tissue. 99mTC-sestamibi scans may assist in differentiating neoplastic (99mTC-sestamibi positive) from non-neoplastic tissue (99mTC-sestamibi negative). Previous literature showed sestamibi to be helpful in detecting residual choroid plexus tumors resulting in further resection. Here, we report the first case to show that sestamibi scans can also help with the opposite decision.

Expression of EAAT-1 distinguishes choroid plexus tumors from normal and reactive choroid plexus epithelium

Microscopic distinction of normal choroid plexus (CP) from choroid plexus tumors (CPT) may be difficult, especially in small samples of well-differentiated CP papillomas. So far, there are no established markers that reliably distinguish normal and neoplastic CP epithelium. Recently, a correlation between expression/function of glial glutamate transporters EAAT-1 (GLAST) and EAAT-2 (Glt-1) and tumor proliferation has been reported. Furthermore, we previously found that CPTs frequently express EAAT-1, but not EAAT-2. We now compared expression of EAAT-1, EAAT-2 and GFAP in non-neoplastic CP (n = 68) and CPT (n = 79) by immunohistochemistry. Tissue of normal CP was obtained from 50 autopsy cases (20 normal and 30 pathologic brains) and 18 neurosurgical specimens that included 17 fetal, 21 pediatric and 30 adult cases. In non-neoplastic postnatal CP (n = 51), focal expression of EAAT-1 was found in only two pediatric cases (4%). In CPT, expression of EAAT-1 was found in 64 of 79 (81%) tumor samples and was significantly age-dependent (P < 0.0001). Hence, EAAT-1 expression distinguishes neoplastic from normal CP, both in children (P = 0.0032) and in adults (P < 0.0001). Immunostaining for EAAT-2 in selected samples from cases of different ages showed that normal CP (n = 15) or CPT (n = 16) lacked EAAT-2 expression. GFAP expression was found in 3 of 32 (10%) normal CP and in 28 of 73 (38%) tumor samples. In conclusion, in contrast to neoplastic CP samples, expression of EAAT-1 is exceptionally rare in non-neoplastic CP. Thus, EAAT-1 is superior to GFAP as a helpful diagnostic tool in CP samples.

Metastasis of a histologically benign choroid plexus papilloma: case report and review of the literature

Cerebrospinal metastases of benign choroid plexus papillomas (CPPs) are extremely rare. We report a case of 32-year-old woman who presented with a 6-month history of vertigo and intermittent headache. Plain CT scan of the cranium revealed a partly calcified tumor filling the fourth ventricle and its right recess. Cranial MRI showed an inhomogeneously contrast-enhancing tumor and leptomeningeal enhancement encasing the brain stem. Complete resection of the tumor was carried out, and seedings to the floor of the fourth ventricle and cervico-medullary junction were found during the operation. While intraoperative frozen section suggested pathology of papillary ependymoma or CPP, to our surprise, final histological examination revealed a benign choroid plexus papilloma. One month after the first operation, a metastatic nodule was found in the spinal subarachnoidal space at the level of T8-9. Two months after the first operation, on follow-up MRI of the cranium, the leptomeningeal enhancement encasing the brain stem had resolved spontaneously. This special case helps increase our understanding of benign CPPs and expands our differential diagnostic consideration of lesions with similar manifestations.

Prognostic Implications of Atypical Histologic Features in Choroid Plexus Papilloma

The prognostic significance of atypical histologic features in choroid plexus tumors remains uncertain. Therefore, a series of 164 choroid plexus tumors was evaluated for the presence of atypical histologic features, including mitotic activity, increased cellularity, nuclear pleomorphism, blurring of papillary growth pattern, and necrosis. The impact of histopathologic and clinical features on the probability of recurrence and survival was investigated. Twenty-four tumors displaying frank signs of malignancy were diagnosed as choroid plexus carcinoma according to World Health Organization criteria. Of 124 choroid plexus papillomas that had not received adjuvant treatment, 46 tumors (37%) displayed at least one atypical feature, including increased cellularity (n = 25 [20%]), mitotic activity (> or =2 mitoses per 10 high-power fields; n = 19 [15%]), nuclear pleomorphism (n = 16 [13%]), solid growth (n = 15 [12%]), and necrosis (n = 5 [4%]). Only one tumor-related death, but 10 recurrences, were observed on a mean observation time of 58 months. On univariate analysis, incomplete surgical resection (p = 0.03) and mitotic activity (p < 0.001) were the only clinicopathologic factors associated with recurrence. Using a multivariate model, an independent effect of mitotic activity on the probability of recurrence could be confirmed (p = 0.001). Because mitotic activity is the sole atypical histologic feature independently associated with recurrence, we propose to define atypical choroid plexus papilloma by mitotic activity (> or =2 mitoses per 10 high-power fields) corresponding to World Health Organization grade II, thus adjoining other intermediate tumor entities associated with increased mitotic activity such as atypical meningioma. Close follow up of patients harboring atypical choroid plexus papillomas may be warranted.

INI1 Protein Expression Distinguishes Atypical Teratoid/Rhabdoid Tumor from Choroid Plexus Carcinoma

Central nervous system atypical teratoid/rhabdoid tumor (AT/RT) and choroid plexus carcinoma (CPC) are rare, highly malignant tumors that predominantly arise in infants and young children. Overlapping clinical, histologic, ultrastructural, or immunophenotypic features may obscure the diagnosis in some cases. AT/RT is characterized by deletions and/or mutations of the INI1 tumor-suppressor gene on chromosome band 22q11.2. We have recently developed an INI1 immunohistochemical staining assay. Negative staining of tumor cells resulting from inactivation of the INI1 gene is a consistent feature of AT/RT. Mutations of INI1 in some CPCs have been reported. The purpose of the present study was to determine if immunohistochemical staining with an INI1 antibody would provide a sensitive means of distinguishing between CPC and AT/RT. We examined 28 tumors with a submitted diagnosis of CPC. Twenty-one CPCs showed retained expression of INI1 and seven tumors showed loss of INI1 expression. Cytogenetic, FISH, and/or INI1 mutation results were also available for 13 tumors. In three of the seven cases, monosomy 22 was the only cytogenetic abnormality, suggestive of AT/RT. However, monosomy 22 was also identified in 3 tumors with complex karyotypes that retained INI1 expression. The 7 tumors that were immunonegative for INI1 had features that were consistent with AT/RT. Immunostaining for INI1 protein is retained in the majority of CPC and is lost in AT/RT. This expression pattern seems to better define the 2 groups of tumors than does light or electron microscopy, routine immunohistochemistry, or cytogenetic analysis alone.

Choroid plexus carcinoma presented with spinal dysfunction caused by a drop metastasis: a case report

A 2-year-old girl demonstrating gait disturbance and dysuria was evaluated and showed two large remote tumors at the left lateral ventricle and lower spinal canal. Pathological analysis demonstrated both of the tumors to be choroid plexus carcinoma (CPC) with high MIB-1 labeling index. The enhanced mitotic propensity would have contributed to an early stage of drop metastasis from the primary site to the sacral sac and following accelerated formation of a longitudinal tumor, which had grown in the subarachnoid space conforming to the spinal canal and finally caused the presenting symptoms of spinal dysfunction. This report shows that CPC can develop exophytically in the subarachnoid space as well as in the ventricle simultaneously before appearance of clinical symptoms and confirms the importance of extensive neuroimaging in its evaluation.