NEURORADIOLOGY

Imaging Findings
Study shows a hyperdense enhancing mass lesion in the region of the pineal gland with mass lesions in the left temporal lobe, and enhancement of the cerebellar folia.

Diagnosis
Pineal Gland Tumor with mets (CSF spread)

Discussion 

Introduction
Pineal region tumors are rare, comprising about 1% of adult and 3% to 8% of pediatric brain tumors. Pineal region tumors include tumors that arise in the pineal gland as well as a small proportion of those that arise in the suprasellar region. However, most suprasellar tumors, such as craniopharyngiomas and pituitary adenomas, are obviously not of pineal origin.

Clinical Features
Tumors of the pineal region can produce a variety of symptoms, including symptoms of increased intracranial pressure (eg, headache, nausea, vomiting, and seizures related to ventricular outflow obstruction), disturbances of gaze due to compression of the mesencephalon, and various endocrine or motor/sensory disorders related to compression of the hypothalamus or cerebellum, respectively.

Types of Pineal Gland Tumors
The three major categories are tumors of germ cells, pineal parenchymal cells, and supporting tissues.

Germ Cell Tumors
Pineal region germ cell tumors arise from embryologic germ cell rests that reach the gland after aberrant migration during early development. As a group, germ cell tumors are the most common pineal tumors. Pineal germ cell tumors tend to occur in adolescence and young adulthood and are rare in females.

The most common pineal tumor is the germinoma, accounting for more than 50% of all tumors occurring in the gland. It is a malignant tumor that typically affects young males in their teens or twenties. Germinomas may be well circumscribed or infiltrative, and they have a high propensity for seeding the spinal cord, and typically, germinomas engulf a calcified pineal gland. Pineal teratomas, and other germ cell tumors such as yolk sac tumor, choriocarcinoma and embryonal carcinoma can also occur, but are rare, and prognosis is poor.

Pineal Parenchymal Tumors
Pineal parenchymal tumors can be divided into undifferentiated pinealoblastomas, well-differentiated pinealomas, and intermediate and mixed types. The pinealoblastoma is a highly malignant tumor that affects children and young adults and occurs more frequently in males. The tumors tend to be ill defined and infiltrative, with a propensity to metastasize to the spinal cord.

Pinealomas are benign tumors that tend to affect people in mid to late adulthood, with no sex predilection. Prognosis after excision is excellent.

Supporting Tissue Tumors
Glial tumors account for up to 33% of pineal tumors and range from low-grade astrocytomas, which are most common, to the highly malignant glioblastoma multiforme. Pineal ependymomas, oligodendrogliomas, and choroid plexus papillomas are rare.

Imaging Findings
Germ cell tumors tend to be very homogenous masses on CT and MR and are always slightly denser than normal brain on NCCT. On MR they are isointense to gray matter on T1, and iso/ sightly hyper intense on T2WI. Both CEMR and CECT display homogenous enhancement of the tumor. Intrinsic pineal tumors are usually similar in appearance: partially calcified, and hyperdense on NCCT, with dense enhancement. Pineal gland may also harbor another PNET, and this condition with bilateral ocular lesions is called trilateral retinoblastoma.

References

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