Pineal tumor

Due to the anatomical location of the pineal gland, space-occupying lesions in this area typically result in pressure on the surrounding brain tissue (mass effect), causing the following symptoms:

• The leading symptom is a buildup of cerebrospinal fluid, also called hydrocephalus. Patients then usually suffer from headaches, nausea, fatigue or memory problems.
• On rare occasions, acute headache may also occur due to sudden hemorrhage or circulatory disturbance caused by the tumor.
• If brainstem compression occurs, patients may notice double vision or other eye movement problems.
• Sometimes hormonal disturbances may also occur if the tumor exerts pressure on the pituitary gland (hypophysis).
• In the case of drop metastases in the spine, these can constrict the spinal cord or nerve roots and lead to neurological deficits and pain *, *, *.

Magnetic resonance imaging (MRI) is considered the gold standard, showing abnormalities in the pineal area.

Occasionally, the cyst wall of a pinealis cyst can be visualized with the use of contrast material. Pinealis cysts are very common benign changes in the area of the pineal gland. However, irregularities of the cyst wall such as nodular changes may indicate a potentially malignant mass.

Insufficient for diagnosis is computed tomography (CT), in which the signal of the cyst often corresponds to that of the cerebrospinal fluid and can therefore also provide a false diagnosis.

In addition, it is recommended to complete the imaging diagnosis with supplementary MRI images of the entire spine to exclude drop metastases *, *.

For a definitive diagnosis, the tumor tissue must be analyzed on a histological basis. First, tissue from the tumor is surgically removed by resection or biopsy. The tissue is then processed by a pathologist. For this purpose, it is stained with special stains and analyzed and evaluated under the microscope *, *, *, *. It takes an average of 3–5 days to receive the fine tissue examination results.

There are a variety of different types of pineal tumors that require different therapy. Here at Inselspital, the specific therapy is determined by our interdisciplinary tumor board consisting of neurosurgeons, neurologists, neuroradiologists, oncologists and radiation oncologists – depending on the results from the fine tissue examination and the tumor markers.

On the one hand, there is pineocytoma, a well-differentiated, benign tumor. In the case of pineocytoma, surgical resection is the treatment of choice. If complete resection is not possible, surgery is followed by complementary radiotherapy.

On the other hand, there is pineoblastoma, a malignant tumor that belongs to the primitive neuroectodermal tumors (PNET).

Both pineocytoma and pineoblastoma can metastasize via CSF drainage and respond well to radiotherapy. However, radiotherapy is not recommended for children under 3 years of age. This is because of the increased side effects on the still-developing brain.

Without treatment, 91% of patients show tumor growth within 2 years. In contrast, over 50% of treated patients continue to show stable conditions after 5 years *, *, *.

Germ cell tumors are divided into germinomas and non-germinomatous germ cell tumors (NGGCT).

Germinomas usually do not require resection and can be treated with radiotherapy only. In this case, a 10-year survival rate of > 90% is shown.

In NGGCT, a further distinction is made between embryonal carcinomas, choriocarcinomas and endodermal sinus tumors (yolk sac tumors). These are treated by radiochemotherapy, a combination of radiotherapy and chemotherapy *, *, *.

For the surgery, the patient's head is fixed with a 3-point holder. With the help of neuronavigation, the most recent MRI images of the patient are matched with the current fixed head position.

After the skin incision, the skull bone is opened with a special bone saw. This is most usually performed from behind, above the cerebellum in the border between the cerebrum and the cerebellum (infratentorial supracerebellar approach). Usually, it can be approached from the midline, but the exact access route is planned and determined by the surgeon based on MRI images and the exact location of the tumor.

The meninges, also called dura, follow below the skull bone and are opened in the next step.

Under microscopic control and with the aid of neuronavigation, the tumor is exposed with as little tissue damage as possible, taking into account the surrounding structures. Once this is done, the resection is performed. The maximum extent of resection depends on the extent to which the tumor has infiltrated the surrounding tissue.

After thorough hemostasis, the dura is tightly closed again.

The previously removed skull bone is correctly repositioned and fixed in place using thin titanium plates and screws.

Finally, the wound is closed with staples or sutures.

After surgery, patients come to our monitoring ward for close neurological monitoring. With a normal course, patients can usually be transferred back to the ward on the 1st or 2nd day after surgery. During this period, a new MRI is also performed to check the extent of resection postoperatively. Further therapy planning depends on this *, *, *.

In patients with hydrocephalus, internal CSF drainage via a ventriculoperitoneal shunt may be considered as an alternative. An endoscopic third ventriculocisternostomy (ETV), in which a short-circuit connection is made between the internal and external cerebrospinal fluid spaces, may also be considered. Here, however, samples of the cyst are not taken for examination *, *, *, *.