Year : 2009 | Volume
: 52 | Issue : 3 | Page : 405--407
Choroid plexus carcinoma: Report of two cases
Avninder Singh, Sarvjot Vermani, Sharma Shruti
Institute of Pathology - ICMR, New Delhi, India
213-B Sukhdev Vihar, New Delhi - 110 025
Choroid plexus carcinomas (CPCs) are rare malignant counterparts of choroid plexus papilloma which occur in infants and children with a predilection for the posterior fossa and have a poor prognosis. We report two cases of CPC diagnosed in a 5-year-old boy and a 12-year-old boy and discuss the clinicopathologic features.
|How to cite this article:|
Singh A, Vermani S, Shruti S. Choroid plexus carcinoma: Report of two cases.Indian J Pathol Microbiol 2009;52:405-407
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Singh A, Vermani S, Shruti S. Choroid plexus carcinoma: Report of two cases. Indian J Pathol Microbiol [serial online] 2009 [cited 2021 Jun 20 ];52:405-407
Available from: https://www.ijpmonline.org/text.asp?2009/52/3/405/55009
The intraventricular central nervous system neoplasms arising from the choroid plexus (CP) without histopathological features of glial, ependymal or meningeal differentiation are termed as choroids plexus tumors.  They account for 0.4% of all brain tumors and histologically show loss of papillary architecture, some areas of CP differentiation, cytological atypia, necrosis and mitotic activity.  We report two cases of choroid plexus carcinoma (CPC) diagnosed in a 5-year-old boy and a 12-year-old boy and discuss the clinicopathologic features.
A 5-year-old boy presented with headache of 2 months duration with no history of seizures or focal neurological deficit. Computed tomography (CT) findings revealed an isodense to hyperdense lesion in the white matter of the left occipito-temporo-parietal region with heterogeneous contrast enhancement. Perilesional edema and mass effect evidence suggested a possibility of glioma. Operative details showed it to be a firm, nonsuckable highly vascular tumor. Grossly , there were multiple friable bits together measuring 4 cm x 3.5 cm x 2 cm. A histological examination showed tumor cells in sheets and clusters, a perivasular pseudopapillary pattern, cells with a high N:C ratio, vesicular to pleomorphic nuclei, eosinophilic cytoplasm along with high mitotic activity and necrosis. Focal areas showed blurred CP differentiation [Figure 1].
A 12-year-old boy presented with headache and vomiting of 2 months duration. CT findings revealed a hyper dense mass in the white matter of the occipito-parietal region with heterogeneous contrast enhancement. Operative details showed it to be a grayish-pink, lobulated, mildly suckable mass. Grossly, multiple friable bits altogether measuring 5 cm x 5 cm x 2 cm were received. Histopathological examination showed malignant tumor cells in stratified layers, a perivascular and pseudopapillary pattern along with ribbons of necrosis in between the sheets of tumor cells [Figure 2].
A histopathological differential diagnosis of CPC and anaplastic ependymoma was considered in both and immunohistochemistry was performed for CK, S100, synaptophysin, CEA and GFAP. Our case showed immunoreactivity to CK, S100, CEA, vimentin and focally for GFAP thus establishing it to be a CPC.
CP tumors represent only 0.4-0.6% of human intracranial tumors and occur most frequently in children where they represent 2-3% of brain tumors.  CP tumors are currently classified into two major groups, papilloma (CPP) and carcinoma (CPC), distinguished by histological features. The distinction between CPP and CPC is not always obvious and histologic characteristics do not always predict biologic behavior. Radiologically, both appear more or less similar.
The CPPs and CPCs are confined to areas where CP is found in the lateral ventricle (50%), fourth ventricle (40%) and third ventricle (5%) CPCs are very uncommon in the fourth ventricle in children, although this is a common site in adults. ,, This neoplasm appears to have a predilection for the posterior fossa and a misdiagnosis was possible before the advent of immunohistochemistry.
The differential diagnosis of posterior fossa tumors other than CPCs includes medulloblastoma, atypical teratoid/rhabdoid (AT/RT) tumors, papillary anaplastic ependymoma and metastatic papillary tumors of extracerebral origin. 
Histologically, medulloblastomas are densely cellular lesions composed of small cells with hyperchromatic, oval to carrot-shaped nuclei with nuclear moulding and scant cytoplasm. Prominent mitotic activity and single cell necrosis are common. Ependymomas are densely cellular tumors showing a perivascular pseudorosette and occasionally true rosette formation. They are composed of oval cells with a dense, speckled nucleus, tapering eosinophilic cytoplasm with prominent background fibrillarity. Anaplastic ependymomas additionally have histological features of malignancy, such as mitotic activity, pleomorphic nuclei and necrosis. Differential diagnosis between CPC and AT/RT tumor may sometimes be difficult. The main criteria favoring CPC were homogeneity of the histological picture, without heterologous elements often found in AT/RT, such as mesenchymal areas, and epithelial differentiation into both squamous and glandular tissue.  AT/RT are characterized by polygonal large rhabdoid cells with eosinophilic cytoplasm and intracytoplasmic inclusions. Areas of primitive neuroepithelial differentiation may be seen. Primary CPC must be distinguished from metastatic papillary tumors originating from tumors of the gastrointestinal tract, kidney, bladder, pancreas and thyroid gland.
CPCs frequently express CK and focal GFAP while CEA and transthyretin proteins are expressed on tissue and are also detected in the peripheral blood.  Synaptophysin helps in differentiating CPCs from metastatic papillary tumors of extracerebral origin and from anaplastic ependymoma, which are immunoreactive for GFAP and negative for EMA and CK. 
The CPCs mainly show chromosomal gain of 1q, 4q, 10q, 14q, 20q and 21q and deletions of 5p, 9p, 15q and 18q.  INI1 immunoexpression was till now considered the single most useful marker to differentiate CPC from AT/RT; however, recent genetic studies have shown important similarities between CPCs and AT/RT, both of which show inactivating mutations of the hSNF5/INI-1 gene in chromosome 22q11.2. This indicates a close relationship between these two entities and needs further studies. 
CPC usually grow rapidly and have a 5-year survival rate of less than 50%. Although gross total resection is by far the best way of prolonging survival, there are conflicting reports of the role of adjuvant chemotherapy.
To conclude, histopathological features like distortion of papillary architecture, layers of CP epithelial cells with pleomorphism and high N:C ratio, presence of mitoses, necrosis and brain invasion are highly suggestive of CPC and help in differentiating from other intraventricular papillary tumors. Also, with the advent of specific immunohistochemical and molecular markers, it is critical to differentiate CPC from its radiological and histopathological mimics for its optimal management.
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