1	Tumors and Tumor-like Lesions of the Pineal Region: MR Imaging Findings Yukunori Korogi, M.D. Department of Radiology University of Occupational & Environmental Health School of Medicine Kitakyushu, JAPAN
2	List of pineal region masses Germ cell tumors Pineal parenchymal cell tumors Glioma Meningioma Metastases Nonneoplastic masses: pineal cyst, lipoma, epidermoid, vascular malformations
3	Pineal gland neoplasms Pineal gland neoplasms are relatively uncommon. Pineal cysts, on the other hand, are remarkably common as incidental findings. Germ cell tumors (GCTs) are also not so uncommon in the oriental countries. The pineal lesions tend to protrude anteroinferiorly to the tectal plate and posterior portion of the third ventricle, leading to hydrocephalus despite of the small mass.
4	Pineal gland neoplasms MR imaging has allowed a marked improvement in the preoperative delineation of benign and malignant pineal masses and in distinguishing true pineal masses from parapineal masses impinging into the region of the gland. In this exhibit, I will review the radiological findings of the pineal region tumors focusing on the MR findings.
5	Diagnosis, please!
6	Diagnosis, please!
7	Pineal gland neoplasms It is difficult to differentiate the pineal GCTs from pineal parenchymal tumors with only images, and age, sex, tumor markers as well as presence of cystic components are important.
8	Pineal region masses Germ cell tumors Pineal parenchymal cell tumors Glioma Meningioma Metastases Nonneoplastic masses: pineal cyst, lipoma, epidermoid, vascular malformations
9	Germ cell tumors GCTs account for 0.5% to 3% of primary intracranial tumors in adults and 12% in children, with a relative high incidence in Japan as well as oriental countries. The age-adjusted GCTs incidence in Japan is reported to be 0.17 per 100,000 population per year (male 0.3, female 0.07). Most patients with GCTs are between 10 and 30 years old; the peak age of presentation is the second decade.
10	Germ cell tumors GCTs are most commonly located in the pineal region; their next most frequent site of occurrence is the hypothalamic-neurohypophyseal region. In the latter case, the earliest symptom is diabetes insipidus. Pineal GCTs affected males predominantly, while suprasellar GCTs have no preponderance of sex.
11	Classification of GCTs Germinoma Teratoma (mature teratoma and immature teratoma) Embryonal carcinoma Choriocarcinoma Yolk sac tumor (endodermal sinus tumor) Mixed GCT which contains more than two components of above
12	Classification of GCTs Germinomas are the least differentiated of the germ cell group. Teratomas differentiate along all three cell lines (ectoderm, mesoderm and endoderm). Germinoma: 40%, Teratoma: 20%, Mixed GCTs: 30%. In mixed GCT, germinoma/teratoma is most common. Pure type of york sac tumor, choriocarcinoma, and embryonal cell tumor is very rare.
13	Imaging findings of GCTs The solid components of the GCTs are iso- to slightly hypointense relative to the gray matter on T1WI, and mixed iso- and hyperintense on T2WI. Contrast MR images are essential for evaluation of GCT. After IV injection of Gd-DTPA, almost all lesions are enhanced markedly and heterogeneously. The heterogeneity varied from mildly to severely. Unlike the previous contrast CT and MRI reports, which showed homogeneous enhancement, the heterogeneous enhancement is common findings.
14	Germ cell tumors Germinoma Teratoma (mature teratoma and immature teratoma) Embryonal carcinoma Choriocarcinoma Yolk sac tumor (endodermal sinus tumor) Mixed GCT which contains more than two components of above
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16	Cystic components of GCTs With a high-resolution MRI, cystic components are more frequently seen than reported before; about 50% of germinomas and 90% of other GCTs have cystic components. The lesions reveal either multiple microcystic components or several macrocystic components.
17	Germinoma with large cystic component
18	Germinoma with synchronous lesions
19	Synchronous lesions About 10% of all intracranial GCTs are the synchronous lesions in pineal and neurohypophyseal regions. This kind of tumor often shows some similarity: the small pineal mass and the symmetric infundibular thickening. There have been two hypothesis about the synchronous masses: dissemination theory and multicentric origination theory.
20	Germ cell tumors Germinoma Teratoma (mature teratoma and immature teratoma) Embryonal carcinoma Choriocarcinoma Yolk sac tumor (endodermal sinus tumor) Mixed GCT which contains more than two components of above
21	Mature teratoma Strikingly heterogeneous Often have dense calcification Marked high intensity of teratoma on both T1WI and T2WI probably representing high protein liquid. Fatty tissues is relatively uncommon in the intracranial teratomas.
22	Germ cell tumors Germinoma Teratoma (mature teratoma and immature teratoma) Embryonal carcinoma Choriocarcinoma Yolk sac tumor (endodermal sinus tumor) Mixed GCT which contains more than two components of above
23	Mixed GCT (Germinoma/Mature teratoma) Imaging findings of mixed GCT is usually nonspecific. It is possible to identify components of germinoma or teratoma.
24	Mixed GCT (Choriocarcinoma/germinoma)
25	What is your diagnosis? A 4-year-old boy presented with precocious puberty such as a rapid increase of body height (10cm/year), enlargement of the penis, and growth of the pubic hair.
26	"Results of endocrine examination" Results of endocrine examination serum testosterone: 413ng/dl (3-20) serum human chorionic gonadotropin (hCG) : 17.1mIU/ml (<0.5) serum alpha-fetoprotein (AFP) level was normal range.
27	MR findings A pineal cyst with enhancement of the slightly thickened wall and focal wall irregularity. It may be difficult to distinguish the lesion from a pineal cyst by the MR images.
28	Diagnosis Germinoma with syncytiotrophoblastic giant cells (STGC) mimicking pineal cyst
29	Germinoma with STGC A subtype of germinoma The syncytiotrophoblastic giant cells produce hCG. Serum hCG level for choriocarcinoma was reported more than 2000 mIU/ml, while that for germonima with STGC was less than 1000 mIU/ml. Germinomas with STGC recur locally more frequently and earlier than pure germinoma.
30	Serum AFP and hCG in GCTS
31	Pineal region masses Germ cell tumors Pineal parenchymal cell tumors Glioma Meningioma Metastases Nonneoplastic masses: pineal cyst, lipoma, epidermoid, vascular malformations
32	Pineal parenchymal cell tumors Pineocytoma & pineoblastoma Tumors that arise from pineal parenchymal cell account for less than 15% of all pineal region neoplasms. Unlike germinomas these tumors may be found in patients beyond the third decade of life.
33	Pineal parenchymal cell tumors Pineocytomas are benign, well-delineated tumors with mature cells that are histologically almost indistinguishable from normal pineal parenchyma. Pineoblastomas are malignant neoplasms that are composed of undifferentiated or immature pineal cells. Transitional type of pineocytoma/–blastoma is also common.
34	Pineocytoma More common in adult Solid tumor with calcification No invasion into the adjacent tissues
35	Pineoblastoma Relatively younger patient than pineocytoma Essentially isointense to gray matter on T2WI, possibly related to the known paucity of cytoplasm and overall dense cellularity seen in these lesions. May also show brain edema or invasion in the surrounding brain parenchyma.
36	Pineal parenchymal cell tumors The reports of image findings for pineal parenchymal tumors varied greatly. The specific diagnosis of histopathologic type in pineal cell tumors is often not possible with MRI.
37	Pineal region masses Germ cell tumors Pineal parenchymal cell tumors Glioma Meningioma Metastases Nonneoplastic masses: pineal cyst, lipoma, epidermoid, vascular malformations
38	Gliomas Pineal region glial cell tumor usually extend from brain parenchymal structures that lie in close proximity to the pineal gland, such as brainstem, corpus callosum as well as thalamus, and only rarely originate from the stroma of the pineal gland itself.
39	Anaplastic Astrocytoma
40	Gliomas The gliomas from thalami or corpus callosum tend to be higher grade: anaplastic astrocytoma or glioblastoma. Tectal gliomas are usually low-grade astrocytomas that enlarge the tectum. The aqueduct may be engulfed and occluded, resulting in obstructive hydrocephalus.
41	Ependymoma
42	Pineal region masses Germ cell tumors Pineal parenchymal cell tumors Glioma Meningioma Metastases Nonneoplastic masses: pineal cyst, lipoma, epidermoid, vascular malformations
43	Meningioma Pineal region meningiomas usually extend from adjacent tentorial apex. Relationship to the falx and tentorium as well as the thickening of the adjacent dura are important for differential diagnosis.
44	Pineal region masses Germ cell tumors Pineal parenchymal cell tumors Glioma Meningioma Metastases Nonneoplastic masses: pineal cyst, lipoma, epidermoid, vascular malformations
45	Metastatic tumor Very rarely, metastasis to the pineal parenchyma can occur and mimic the primary pineal gland masses. Signal intensity patterns and contrast enhancement of pineal metastases on MRI are usually nonspecific and basically the same as in other locations.
46	Pineal region masses Germ cell tumors Pineal parenchymal cell tumors Glioma Meningioma Metastases Nonneoplastic masses: pineal cyst, lipoma, epidermoid, vascular malformations
47	Pineal cyst Unlike pineal tumors, pineal cysts are benign, usually asymptomatic and found incidentally on MRI. The pineal cysts are lined by collagenous fibers, glial cells, and normal pineal parenchymal cells. The prevalence found on MRI in health subjects is 1.4-4.3%, and seen in up to 40% of routine autopsies.
48	Pineal cyst The pineal cysts are round and smoothly marginated on MRI, and have thin smooth walls no more than 2 mm. The contents of the pineal cyst are usually homogenous, and are either isointense to cerebrospinal fluid or diffusely hyperintense. The pineal cyst usually does not enhance, but surrounding residual pineal tissue will.
49	Pineal cyst Although the size of the cyst may change in the follow-up, they were not associated with specific clinical findings. Occasionally, the imaging appearance of benign pineal cyst is indistinguishable from small cystic neoplasms.
50	Rare pineal region masses Dermoid Epidermoid Cavernous hemangioma Hemangiopericytoma Melanoma Craniopharyngioma Malignant rhabdoid tumor Choroid plexus papilloma Paraganglioma Ganglioglioma Ganglioneuroblastoma Malignant lymphoma Arachnoid cyst
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52	Cavernous hemangioma
53	Summary MR imaging is useful for delineation of benign and malignant pineal masses and for distinguishing true pineal masses from para-pineal masses. Generally, however, MR findings are nonspecific, and age, sex, tumor markers as well as presence of cystic components are important for differential diagnosis.
54	References Y. Korogi, M. Takahashi, U. Ushio. MRI of pineal region tumor. Journal of Neuro-oncology 54:251-261,2001 L. Liang, Y. Korogi, T. Sugahara, et al. MRI of Intracranial Germ Cell Tumors. Neuroradiology 44: 382-388, 2002 Osborn AG. Pineal region masses. In Diagnostic Neuroradiology. Mosby, St. Louis, 408-421, 1994 Atlas SW, Lavi Ehud. Intra-axial brain tumors. Atlas SW eds. Magnetic Resonance Imaging of the Brain and Spine. Lippincott-Raven, Philadelphia, 1996,315-422 Committee of Brain Tumor Registry of Japan. The epidemiology and statistic of brain tumors in Japan, 1990 (Japanese). Kuratsu J, Ushio Y. Epidemiological study of primary intracranial tumors: a regional survey in Kumamoto prefecture in the southern part of Japan. J Neurosurg 1996; 84: 946-950. Sugiyama K, Uozumi T, Kiya K, et al. Intracranial germ-cell tumor with synchronous lesions in the pineal and suprasellar regions: report of six cases and review of the literature. Surg Neurol 1992; 38:114-120 Sumida M, Uozumi T, Kiya K, et al. MRI of intracranial germ cell tumors. Neuroradiol. 1995; 37: 32-37.
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