Metastases to the choroid plexus from extracranial tumors are rare, but nonetheless should be included in the differential diagnosis of an intraventricular mass. They are most commonly found within the lateral ventricles, presumably because a large proportion of the choroid plexus is located there.
Choroid plexus metastases account for <5% of intracranial metastases in autopsy series, and <1% of clinically evident cerebral metastases 1,4. They are seen most commonly in adults, although have also been found in children with extracranial childhood tumors.
Tumor spread to the choroid plexus may occur through a hematogenous route via the anterior or posterior choroidal arteries 4,6, or through CSF seeding 4.
Tumors most likely to metastasize to the choroid plexus are renal cell carcinoma and lung cancer. Other tumors with documented spread to the choroid plexus include colon, gastric, breast, thyroid, and bladder cancers, melanoma, lymphoma, and carcinoma of the esophagus 7.
Choroid plexus metastases may be seen on CT or MRI as either a solitary lesion or as a component of disseminated intracranial metastatic disease. Reported complications which may be found on imaging include hydrocephalus and hemorrhage from an intraventricular metastasis 1.
Imaging appearance is variable. The lesion may be hypo or isodense on non-enhanced CT and may demonstrate moderate or marked enhancement, more commonly homogeneous 6.
MRI is more sensitive than CT in the detection of small choroid plexus lesions.
With larger lesions, there may be peritumoural edema or invasion into adjacent brain parenchyma.
Treatment and prognosis
These lesions may be amenable to surgical resection. Prognosis is variable and depends on the type and stage of the primary tumor, and extent of metastatic dissemination.
The differential diagnosis is that of other intraventricular masses that may arise in the relevant age group. In an adult patient, consider:
- intraventricular meningioma: particularly at the trigone of a lateral ventricle
- colloid cyst: when at the foramen of Monro 5
- central neurocytoma
- subependymoma: particularly if there is poor enhancement
- 1. Koeller KK, Sandberg GD. From the archives of the AFIP. Cerebral intraventricular neoplasms: radiologic-pathologic correlation. Radiographics. 22 (6): 1473-505. Radiographics (citation) - Pubmed citation
- 2. 1357337513883. Kart BH, Reddy SC, Rao GR et-al. Choroid plexus metastasis: CT appearance. J Comput Assist Tomogr. 10 (3): 537-40. - Pubmed citation
- 3. Escott EJ. A variety of appearances of malignant melanoma in the head: a review. Radiographics. 21 (3): 625-39. Radiographics (citation) - Pubmed citation
- 4. Qasho R, Tommaso V, Rocchi G et-al. Choroid plexus metastasis from carcinoma of the bladder: case report and review of the literature. J. Neurooncol. 1999;45 (3): 237-40. - Pubmed citation
- 5. Leach JC, Garrott H, King JA et-al. Solitary metastasis to the choroid plexus of the third ventricle mimicking a colloid cyst: a report of two cases. J Clin Neurosci. 2004;11 (5): 521-3. doi:10.1016/j.jocn.2003.07.001 - Pubmed citation
- 6. Kohno M, Matsutani M, Sasaki T et-al. Solitary metastasis to the choroid plexus of the lateral ventricle. Report of three cases and a review of the literature. J. Neurooncol. 1996;27 (1): 47-52. - Pubmed citation
- 7. Sung WS, Dubey A, Erasmus A, Hunn A. Solitary choroid plexus metastasis from carcinoma of the oesophagus. (2008) Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia. 15 (5): 594-7. doi:10.1016/j.jocn.2007.02.001 - Pubmed