Presentation
Confusion, weakness, aphasia, and several weeks of headache and vomiting.
Patient Data
- large heterogeneous (partly cystic, partly calcified) mass centered in the atrium, occipital horn, and posterior body of the right lateral ventricle
- satellite nodules within the right lateral ventricle temporal and frontal horns suggest CSF dissemination
- entrapment of the temporal horn of the right lateral ventricle
- vasogenic edema in the surrounding brain parenchyma
- mass effect: medialization of the right uncus, effacement of the basilar cisterns, leftward midline shift of 12 mm, deformity of the midbrain/cerebral peduncles
- partially mineralized, partially hemorrhagic right lateral intraventricular neoplasm
- the anterior component has a papillary (frond-like or cauliflower-like) morphology, high vascularity (intense contrast enhancement, high relative blood volume), microhemorrhages (punctate susceptibility effect, appearing bright on phase map similar to veins), T2 hyperintensity throughout, and facilitated diffusion
- the posterior and superior component has an irregular morphology (conforming to the contour of the ventricle but expanding it), low vascularity (mild contrast enhancement, low relative blood volume), calcifications (stippled susceptibility effect, appearing dark on phase map in contradistinction to veins), T2 hypointensity in the solid components surrounding a cystic/necrotic cavity, and markedly restricted diffusion
- intraventricular metastases as evidenced by multiple nodules coating the ependymal surface of both lateral ventricles and third ventricle, which following the signal characteristics of the irregular posterior component of the dominant mass
- extraventricular metastases as evidenced by leptomeningeal enhancement involving cisternal segments of both trigeminal nerves and right spinal accessory nerve at the foramen magnum
- mild vasogenic edema in the surrounding brain parenchyma
Case Discussion
The imaging appearance of a cauliflower-like hypervascular intraventricular mass plus a more irregular and hypercellular component with CSF dissemination, in a child, strongly suggested a choroid plexus carcinoma. The differential diagnosis included a germ cell tumor, but bloodwork did not reveal any suggestive biomarkers. Other considerations included intraventricular glioblastoma, intraventricular ependymoma, and primitive neuroectodermal tumor. Given the evidence of CSF dissemination, total spinal imaging was also performed as part of the initial staging (as well as follow-up studies), which did not reveal a definite distant deposit.
The patient underwent craniotomy for partial resection (to be followed by chemotherapy and craniospinal radiotherapy).
Pathology report:
High-grade neoplasm with choroid plexus differentiation and embryonal morphology, suggestive of choroid plexus carcinoma.
Sections show a densely cellular biphasic tumor with two distinct components. One consists of sheets of markedly pleomorphic and discohesive cells with scant cytoplasm consistent with a primitive neuronal or embryonal appearance, with scattered bizarre and multinucleated giant cells. Mitotic figures are frequent and necrosis is present. The other component consists of complex papillary epithelioid structures resembling choroid plexus, with scattered mitotic figures, including atypical mitoses. The transition between these two components is mostly abrupt, with some foci showing a gradual transition.
Immunohistochemical staining performed on block A3 shows that both components of the tumor are diffusely positive for synaptophysin. S100, AE1.3/CAM5.2 and MNF116 predominantly highlight the choroid plexus component and are largely negative in the poorly differentiated component, with some scattered positivity for keratins. There is strong and diffuse p53 nuclear labeling seen in both the poorly differentiated portion as well as the epithelial component. There is focal GFAP and desmin positivity and focal weak staining for transthyretin in the choroid plexus component, while the poorly differentiated component is negative. INI1 and BRG1 show retained nuclear staining throughout (consistent with wildtype). EMA, Oct3/4 and SALL4 are negative.
The overall morphology and immunophenotype are consistent with a choroid plexus neoplasm, suggestive of choroid plexus carcinoma (a WHO grade 3 neoplasm), however, the presence of a primitive/embryonal component is unusual in this context and may affect the biological behavior of this tumor (perhaps resembling a WHO grade 4 neoplasm).
Molecular diagnostics revealed variants in TP53, PTEN, and RB1. Genetic testing for germline TP53 mutations was negative.
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