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Findings: Image #1 demonstrates an approximately 1.5 cm by 1.5 cm iso to hyperdense lesion in the region of the pineal gland.
Image #2 demonstrates calcification within this small mass.
Diagnosis: Pineocytoma.
Discussion: Pineal tumors are relatively uncommon lesions occurring most commonly in children and young adults. Of the various forms of pineal tumors, germ cell tumors constitute the most common type accounting for approximately 60% of all pineal masses. Of the germ cell tumors, germinoma is the most common, with teratoma, choriocarcinoma, and embryonal cell carcinoma being much less common. Tumors of the pineal cell origin are much less common than those of germ cell origin. These include pineocytoma and pineoblastoma. Pineoblastoma is a highly malignant neoplasm occurring primarily in children. They have been categorized in the PNET group.
Pineocytomas (such as seen in this case) are generally benign lesions of the pineal parenchyma occurring predominantly in adults. They are most often well demarcated, noninvasive, homogeneous, and slow growing. They often demonstrate peripherally displaced calcifications and heterogeneous intense enhancement. In general, it is quite difficult currently to make an accurate distinction between germ cell tumors and parenchymal tumors (i.e., pineocytoma) based solely on imaging findings. One possible differentiating feature is the fact that most germ cell tumors will engulf primary pineal calcifications while parenchymal tumor such as pineocytoma or pineoblastoma will produce an exploded appearance of the calcification. The most common clinical presentation is secondary to hydrocephalus due to obstruction of the third ventricle or aqueduct.
References:
Brandt W. Fundamentals of Diagnostic Radiology. Williams and Wilkins,
Baltimore. 1994;139-141.
Yock D. Magnetic Resonance Imaging of CNS Disease. Mosby, St. Louis.
1995;168-173.
Chiechi M. Pineal Parenchyma Tumors: CT and MR Features. J Comput
Assist Tomogr., 1995;(19)4:509-517.
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