Choroid Plexus Carcinoma with Rhabdoid Features: A Case Report
SUMMARY
We present the case of a patient under 2 years of age with acute
vomiting, fever and seizures. MR imaging of the brain revealed a right
lateral intraventricular mass and mild hydrocephalus. Surgery achieved
gross total tumor resection, but tumor histology revealed choroid plexus
carcinoma with heavy stratification and atypical ”rhabdoid” cells.
Choroid plexus carcinomas are extremely rare tumors, and the presence of
rhabdoid cells is even rarer. Correct identification of choroid plexus
carcinomas is essential since the management and prognosis are very
different from benign choroid plexus tumors. Although they seem
morphologically similar, choroid plexus papilloma and choroid plexus
carcinoma have subtle differences that, once identified, allow an
appropriate diagnosis. We present also a review of current literature
highlighting the imaging differences between choroid plexus carcinoma
from papilloma.
ABBREVIATION KEY
CSF= cerebrospinal fluid
WHO= World Health Organization
CPP= choroid plexus papilloma
aCPP= atypical choroid plexus papilloma
CPC= choroid plexus carcinoma
TERT= reverse-transcriptase protein subunit
INTRODUCTION
The choroid plexus is a richly vascularized secretory epithelium
resulting from the invagination of the ependymal roof plate into the
ventricular cavities by the blood vessels of the pia mater, producing
the intraventricular cerebrospinal fluid (CSF) [1]. Tumors
originating from choroid plexus are infrequent, representing less than
1% of all intracranial tumors [2]. According to the histological
classification of the World Health Organization (WHO), they can be
divided into choroid plexus papilloma (CPP), atypical choroid plexus
papilloma (aCPP), and choroid plexus carcinoma (CPC)[3]. The average
annual incidence of all choroid plexus tumors is 0.3 out of 1,000,000
patients per year[4]. It is assumed that malignant tumors arise de
novo [5]. Papillomas account for two thirds of choroid plexus
tumors, they are generally benign and resection is usually curative. In
contrast, carcinomas are malignant lesions with overall survival rates
of 40 to 50% [6]
CASE REPORT:
A previously healthy 14 month old male presents with acute onset of
seizures and a 10 days history of persistent vomiting and fever. Initial
head computed tomography shows a heterogeneous intraventricular
lobulated mass with punctate calcifications and focal intratumoral
cystic areas, peripheral edema and associated hydrocephalus (Figure 1).
An intraventricular shunt was placed for decompression. MRI showed a
lobulated, intraventricular heterogeneous mass, with nodular enhancement
and internal focal areas of diffusion restriction. The lateral posterior
margin of the tumor extend though the ependymal wall into the
periventricular parietooccipital white matter (Figure 2).
Patient had a partial tumor resection though right parietal approach,
finding at surgery a lobulated mass with variable consistency (areas of
friable and of solid tumor) and heterogeneous color going from pink to
gray white. Due to its extension, poor definition of margins and
friability behavior, total tumor resection is not possible.
Histopathology findings shows the presence of papillary structures with
true fibrovascular stems, covered by a population of neoplastic cells,
pleomorphic nuclei, with heavy stratification. Also, atypical ”rhabdoid”
cells are observed, with discrete cell borders, eccentric nuclei, and
abundant eosinophilic cytoplasm Histopathologic diagnosis was choroid
plexus carcinoma (Figure 3). He received intra-arterial neoadjuvant
chemotherapy based on carboplatin, etoposide and ifosfamide, without
initial adverse effects, waiting for a second surgical time to complete
resection.
DISCUSSION
CPC are grade III brain tumors with poor prognosis. The oncogenesis of
this lesion is unknown[7]. CPC could be confused with papillary
ependymomas, malignant meningiomas and embryonal tumors in the pediatric
age, occurring usually in children less than two years of age. In the
adult, it can be confused with metastatic carcinoma. Almost all CPC
occur in infants and children aged 2–4 years, with 70% initially
diagnosed in children less than 24 months of age [2, 3, 6]. Symptoms
are usually due to hydrocephalus, which is of a lesser degree than that
found in CPP [1, 8]. The literature for pediatric populations
indicate that 67 to 75% of all choroid plexus tumors are located in the
lateral ventricles, 15% in the fourth ventricle, and 8% in the third
ventricle; with no difference in location with respect to tumor
histological classifications[9].
Imaging findings are not specific, showing an intraventricular lobulated
mass, that may have punctate calcifications and homogeneous intense
enhancement [5]. On CT scan CPCs appear iso-dense to hyper-dense,
with calcification and avid enhancement. On MRI they usually appears iso
or slight hyperintense on T1-weighted images, and are slightly
hyperintense on T2-weighted images, showing typically intense
enhancement. Serpentine signal flow voids may be present within or near
the tumor, indicating enlarged blood vessels supplying or draining the
tumor. Because papillomas are benign, they tend to expand the ventricle
rather than invade adjacent brain, but both benign and malignant choroid
neoplasms may show focal parenchymal invasion, signal characteristics
and enhancement patterns that could make them indistinguishable [5].
Nevertheless, extensive parenchymal invasion with extension through the
ependymal lining, and peritumoral vasogenic cerebral edema favor
malignant lesions [1, 5]. Both CPP and CPC presents elevated levels
of Choline and absence of N-acetyl aspartate by MR spectroscopy [5,
6].
The neuropathologic criteria established by the World Health
Organization require: 1) obvious invasion of adjacent neural tissue with
the infiltrating cells on a stromal base, with a diffuse and poorly
defined pattern of growth; 2) loss of regular papillary architecture;
and 3) evidence of cellular malignancy (increased mitotic activity,
nuclear atypia, and necrosis) [10]. The epithelial sheath overlying
the papillae can be redundant, exhibiting focal areas of stratification.
Some nuclei can be hyperchromatic, and could find the presence of
rhabdoid cells [5]. Immunohistochemistry is often inconclusive
[5]. CPC could express carcinoembryonic antigen. Molecular findings
include P53 mutations, Li–Fraumeni syndrome and mutations in
reverse-transcriptase protein subunit (TERT)[9].
The surgical plan should include temporary or permanent resolution of
hydrocephalus and definition of the tumor anatomic location, margins and
blood supply. Tumors of the lateral ventricle or third ventricle are
generally supplied by branches of the anterior or posterior choroidal
arteries. Mass effect tends to displace the internal occipital artery
and the basal vein of Rosenthal in an inferior direction[5].
Magnetic resonance angiography may provide more detailed images of the
vascular supply of the tumor. One of the most important predictors of
survival for CPC patients is initial total resection of the tumor, which
can be difficult due to their invasive nature and also their softer and
more friable behavior compared to papillomas [3, 5, 6].
Although carcinomas rarely metastasize from the intracranial or
intraspinal compartment, they can disseminate throughout the CSF
pathways. Spinal MRI is an important modality for detecting spinal drop
metastases. The overall incidence of metastases in CPC is 12–50%
[5]. Combined with adjunctive therapy, radiation, or chemotherapy,
survival after surgery ranges from 67% to 91% [5, 9].
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