Presentation
Fall from height.
Patient Data
Isodense heterogeneous mass measuring 3.4 x 4.2 x 6.6 cm, filling and expanding the left ventricle, centered in the trigone, showing no calcification, enhancing intensely and heterogeneously. Small amount of fresh hemorrhage in the left ventricle, including the left temporal horn. Mild peritumoral vasogenic edema.
CSF spaces of normal width, except for focal dilatation of left temporal horn.
Midline preserved.
The cisterns are open, the craniocervical junction is normal.
Normally aerated paranasal sinuses.
Osseous component preserved.
In summary:
Primary left ventricle mass with small amount of fresh peritumoral bleed. Features compatible with choroid plexus papilloma or choroid plexus carcinoma. Astrocytoma and ependymoma also on the list of differentials.
Solid, well-defined intraventricular mass centered in the atrium of the left ventricle. Shows heterogeneous low signal on T1WI, slightly hyperintense on T2WI, and enhances vividly after contrast administration. Numerous foci of susceptibility artifact on SWI, in keeping with blood degradation products. Several intratumoral vessels. ADC values similar to those of the brain parenchyma. Blood outlines the mass and in small amount in the occipital lobe. Relatively bulky left ventricular choroid plexus. On MR spectroscopy, no NAA peak identified; prominent choline peak; no clear lactate peak. Mild white matter edema around the left atrium; however, no clear evidence of parenchymal infiltration by the mass itself. Mild hydrocephalus, presenting as mild dilatation of lateral and third ventricles, with rounding of anterior recesses of third ventricle; occipital horn of left ventricle dilated by the mass; temporal horns dilated as well, left more than right. Partial effacement of extra-axial CSF spaces. No pronounced periventricular edema. Mild dilatation of CSF sheaths of the optic nerves.
Corpus callosum appears normal. Posterior fossa structures, brainstem, and craniocervical junction preserved.
Head circumference - 51 cm, corresponding to 94th centile for age and sex.
In summary: Solid mass centered in the left atrium. Features most compatible with choroid plexus tumor. The imaging findings are more suggestive of papilloma cf. carcinoma. Lower probability of other intraventricular tumors, e.g. ependymoma. Signs of mild hydrocephalus. No evidence of leptomeningeal spread (spine MRI not shown).
Case Discussion
Fall from inconsiderable height, no loss of consciousness. Vomited once, then spell of sleepiness. Vomited many times afterwards. Approximately 10 days previously, complained of headache and backache, dubitable changes in gait, with intermittent dragging of right foot.
CT and MRI showed an enhancing left ventricular mass. The MRI included the entire spine (not shown here), which was normal. The blood in the same ventricle was probably hemorrhage from the mass itself as a result of the mild head trauma. She received dexamethasone for the edema, then the mass was removed. Recovered remarkably, with no lingering headache.
Histopathology report:
Features most consistent with atypical choroid plexus papilloma, WHO grade II.
The lesion is composed of epithelioid cells that create papillary structures and solid surfaces. Scattered cells with cytologic atypia, hypercellular areas, and areas of necrosis. Up to 2 mitoses/10 HPF counted. Invasion of tumor cells into galeal tissue seen. In addition, scattered calcifications and hyaline globules seen.
On immunohistochemical staining, the tumor cells were partially positive for KERMNF116, S100, and VIM; few cells positive for KER7, GFAP, CD44, EMA, and SYN; negative for KER20. Stains for INI1 and BRG1 were positive (preserved). On staining for p53, ~1-2% of the cells stained (some of the cells showed nonspecific cytoplasmic staining). On staining for Ki67, an average proliferative index of 5-7% was seen.
Discussion: the tumor contains solid areas, necrotic areas, invasion into galeal tissue, and cells with cellular atypia, all of which raise the suspicion of a malignant tumor; however, said findings can be present in atypical papilloma. Nevertheless, mitotic activity is relatively low, only a small percentage of cells stains for p53, and the proliferative index is in more the range of atypical papilloma. In light of this, the findings are more consistent with atypical choroid plexus papilloma.
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