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Pineal Region Tumors with Large Cystic Components: Report of Two Cases

Two patients with neurological findings of midline intracranial masses displayed cystic components extending into the thalamus. In one patient, absent tumor markers, nonspecific pathological findings by stereotactic biopsy, and the large thalamic cystic component suggested a diagnosis of astrocytoma rather than germinoma. In the other, cystic neuroimaging findings and the pathological specimen obtained by stereotactic biopsy suggested a thalamic astrocytoma; however, elevated alpha fetoprotein and chorionic gonadotropin levels indicated embryonal cell carcinoma, confirmed by subsequent surgery. Because large cystic components are unusual and usually noted in astrocytomas and teratomas, this report extends the spectrum of imaging findings in pineal region tumors.