Pineal gland tumor

Pineal gland tumor Main page
Patient Information
Overview
Causes
Classification Pineocytoma Pineal teratoma Pineal yolk sac tumor Pineal choriocarcinoma Pineal embryonal carcinoma Pineal germinoma Pineal gland cyst
Pathophysiology
Differentiating pineal gland tumor from Other Diseases
Differentiating features among different various Pineal Gland Tumors

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Fahimeh Shojaei, M.D., Sujit Routray, M.D. [2], Aditya Ganti M.B.B.S. [3]

Synonyms and keywords: Pineal gland tumors; Pineal gland cancer; Pineal gland cancers; Pineal gland neoplasm; Pineal gland neoplasms; Neoplasm of the pineal gland; Neoplasms of the pineal gland; Cancer of the pineal gland; Cancers of the pineal gland; Astrocytoma; Meningioma; Pineal gland; Parinaud syndrome; Brain tumor

Overview

The pineal gland is an endocrine gland that is located in the posterior aspect of the cranial fossa in the brain. The pineal gland is responsible for the secretion of melatonin hormone that regulates the in the circadian cycle sleep and wakefulness. The blood supply of the pineal gland is derived from the posterior cerebral artery from its choroidal branches. The internal cerebral vein drains the blood from the epiphysis cerebri. Histologically the gland consists of cells called pinealocytes. Several different tumors can arise from the pineal gland. Primary pineal cell tumors include pineocytoma, pineoblastoma, and mixed pineal tumors. Tumors that may occur in this region but are not necessarily pineal tumors include germinoma, non-germinoma (eg, teratoma, endodermal sinus tumor, embryonal cell tumor, choriocarcinoma, and mixed tumors), meningioma, astrocytoma, ganglioglioma, and dermoid cysts. Diagnosis of the type of tumor is crucial for treatment. The primary symptom of the tumor would be hydrocephalus. If the pineal gland invades the thalamus, it can cause weakness and loss of sensation in half of the body. Invasion of the hypothalamus would disrupt sleep, impede temperature and water regulation, and cause weight gain. An MRI is important when trying to see the location and size of the tumor. A biopsy is required to determine the type of tumor. Usually, a biopsy is done via a stereotactic or endoscopic procedure. Sometimes biomarkers are used to detect the presence of the tumor, and if these are found in the CSF and blood, then a biopsy might not be needed. Some of these chemicals are beta-human chorionic gonadotropin, carcinoembryonic antigen, and a-fetoprotein.

Classification

Pineal gland tumors are broadly divided into four subcategories. The various types of pineal gland tumors include:

1. Pineal parenchymal tumors: Pineal parenchymal tumors arise directly from the normal functional cells of the pineal gland, pineal parenchymal cells (pineocytes or their precursors), and they are distinct from other pineal gland neoplasms such as astrocytic and germ cell tumors. These tumors are formed after the embryological development of the pineal gland.
2. Pineal germ cell tumors: They are tumors which arise from the embryological abnormalities. They are derived from the germ cells, including sex cells, of the pineal gland during the developmental process of the pineal gland.
3. Astrocytoma of the pineal gland: They arise from the astrocytes, which are a particular kind of star-shaped, glial brain cells around the pineal gland.
4. Pineal metastasis: Pineal metastasis is a cancer that has metastasized to the pineal gland from another location in the body.

Pineal gland tumors

Pineal parenchymal tumors

Astrocytoma of the pineal gland

Germ cell tumors

Pineal metastasis

Pineocytoma

Pineal parenchymal tumor with intermediate differentiation

Papillary tumor of the pineal region

Pineoblastoma

Pineal germinoma

Pineal embryonal carcinoma

Pineal choriocarcinoma

Pineal yolk sac tumor

Pineal teratoma

Pathophysiology

Normal Anatomy

• The pineal gland is a small reddish-brown structure that derives its name from its pinecone-like shape.
• The pineal ranges in size from 10 to 14 mm; it is located in the midline, above the tentorium and superior colliculi and below the splenium of the corpus callosum and the vein of Galen, and is attached to the superior aspect of the posterior border of the third ventricle.
• The blood supply of the pineal gland is derived from the posterior cerebral artery from its choroidal branches.
• The internal cerebral vein drains the blood from the epiphysis cerebri.
• Histologically the gland consists of cells called pinealocytes and supporting cells.

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Embryology

• Pineal gland develops as a diverticulum in the diencephalic roof of the third ventricle during the second month of gestation.
• The mature gland is suspended from the pineal stalk from the posterior roof of the third ventricle.
• The pineal secretes melatonin, which is involved in diurnal rhythms.

Pathogenesis

• Due to the pineal gland's location, any tumor or cyst formation would lead to the compression of the aqueduct of Sylvius.
• The aqueduct of Sylvius allows the cerebrospinal fluid to circulate out.
• When there is a blockage in aqueduct of Sylvius by an abnormal pineal gland, the passage of the duct is blocked, and CSF pressure builds up, leading to hydrocephalus.
  • Results in nausea, vomiting, visual changes, headaches, seizures, and memory changes.
• Increase in intracranial pressure can even be life-threatening, prompting emergency treatment.
• The hydrocephalus can be relieved by the placement of a VP shunt or ventriculostomy.
• Vision changes would also occur due to an involvement of the tectal region.
  • The tectal region helps dictate eye movements.
  • Fault in the tectal region causes double vision, an issue with focusing on objects, and eye movement impairment.
• The pineal gland can cause Parinaud syndrome due to the increasing size of the gland compressing the pretectal area and superior colliculi of the midbrain.
  • Parinaud syndrome prevents a person from moving his or her eyes up and down.
• The thalamus can be affected, and if so, there can be disturbances on that side of the body which would result in weakness and loss of sensation.
• The tumor's effect on the hypothalamus will lead to weight gain, disruption of sleep, disruption of temperature control, and water regulation.
• Cerebellar involvement would result in motor impairment.
  • If the tumor of the pineal gland is present in childhood, then endocrine dysfunctions can also result such as precocious pseudopuberty, diabetes insipidus, and a slowed growth rate.

Pineal choriocarcinoma

• Pineal choriocarcinoma is a relatively rare, malignant, highly vascular neoplasm and accounts for a small proportion of all intracranial germ cell tumors. It is an aggressive tumor and has a propensity to metastasise systemically. Pure pineal choriocarcinoma tumors secrete β-HCG.
• On microscopic histopathological analysis, pineal choriocarcinoma is characterized by presence of intimately related syncytiotrophoblasts and cytotrophoblasts without formation of definite placental type villi. Syncytiotrophoblasts are large multi-nucleated cells with eosinophilic cytoplasm. They often surround the cytotrophoblasts, reminiscent of their normal anatomical relationship in chorionic villi. Cytotrophoblasts are polyhedral, mononuclear cells with hyperchromatic nuclei and a clear or pale cytoplasm.
• Pineal choriocarcinoma accounts for 5% of all pineal masses.
• The peak age at diagnosis for pineal choriocarcinoma is 20-30 years.
• Common complications of pineal choriocarcinoma include:

• CSF metastasis
• Intraventricular hemorrhage
• Coma
• Systemic metastasis

• The clinical presentation of pineal choriocarcinoma is mainly from the obstructive hydrocephalus secondary to compression of the tectum of the midbrain and obstruction of the aqueduct. Symptoms of pineal choriocarcinoma include headache, vomiting, ptosis, and weakness.
• Compression of the superior colliculi can lead to a characteristic gaze palsy, known as Parinaud syndrome.
• Common physical examination findings of pineal choriocarcinoma include papilledema, signs of precocious puberty, restricted extraocular movements, sluggish pupillary light reflex, stiff neck, hemiparesis, and abducent nerve palsy.
• Laboratory findings consistent with the diagnosis of pineal choriocarcinoma include abnormal CSF analysis, demonstrating xanthochromia.
• Head CT scan and brain MRI may be helpful in the diagnosis of pineal choriocarcinoma.
• On head CT scan, pineal choriocarcinoma is characterized by a round, calcified, homogeneous, enhancing mass in the third ventricle associated with the dilation of the lateral and third ventricles and periventricular lucency.
• On brain MRI, pineal choriocarcinoma is characterized by hyperintensity on T1-weighted images and signal drop-out and blooming on T2* sequences.
• Biopsy is generally done to confirm the diagnosis of pineal choriocarcinoma.
• The mainstay of therapy for pineal choriocarcinoma is radiotherapy and/or chemotherapy. Sometimes, surgical resection may be done.

Differentiating pineal gland tumor from Other Diseases

Pineal gland tumormust be differentiated from other diseases that cause seizure, visual disturbance, and constitutional symptoms, such as:

• Oligodendroglioma
• Meningioma
• Astrocytoma
• Pituitary adenoma
• Schwannoma
• primary CNS lymphoma
• Medulloblastoma
• Ependymoma
• Craniopharyngioma
• Hemangioblastoma
• AV malformation
• Brain aneurysm
• Bacterial brain abscess
• Tuberculosis
• Toxoplasmosis
• Hydatid cyst
• CNS cryptococcosis
• CNS aspergillosis
• Brain metastasis

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Differentiating features among different various Pineal Gland Tumors

Tumors	Grade	Pathalogic Features	5-year survival	Cerebrospinal fluid (CSF) dissemination	Imaging
					CT	MRI
Pineocytoma	Grade I lesion	Small, uniform, mature cells that resemble pineocytes Lobular architecture and pineocytomatous rosettes	86%–100%	Rare	Well demarcated, usually less than 3 cm, and iso- to hyperattenuating.	Hypo- to isointense on T1-weighted images Hyperintense on T2-weighted images.
Pineal Parenchymal Tumor of Intermediate Differentiation	Grade II or III	Gross inspection, PPTID is similar in appearance to pineocytoma. It is a well-circumscribed lesion without evidence of necrosis. Histologic evaluation reveals diffuse sheets of uniform cells and the formation of small rosettes, with features intermediate between those of pineocytoma and those of pineoblastoma. Low to moderate levels of mitotic activity and nuclear atypia are seen.	39%–74%	Rare	No specific imaging findings	No specific imaging findings Demonstrate high signal intensity on T2-weighted images and enhance on postcontrast images Cystic areas may also be seen
Pineoblastoma	Grade IV	Pineo-blastomas are highly cellular embryonal neoplasms that resemble other primitive neuroectodermal neoplasms of the central nervous system. Cells have scant cytoplasm and are arranged in diffuse sheets. Homer-Wright rosettes (neuroblastic differentiation) or Flexner-Wintersteiner rosettes (retinoblastic differentiation) may be seen, and hemorrhage or necrosis may be present. Infiltration into adjacent structures and craniospinal dissemination commonly occur	58%	Most common cause of the death	Lobulated, typically hyperattenuating mass, an appearance that reflects its highly cellular histologic features.	Ill-defined enhancing pineal mass with resultant hydrocephalus
Papillary Tumor of the Pineal Region	Grade II or III	PTPRs are well-circumscribed lesions that can measure up to 5 cm and may have a cystic component. At histologic evaluation, they demonstrate an epithelial-like growth pattern, papillary features, rosettes, and perivascular pseudorosettes. The immunohistochemical findings help differentiate PTPR from other lesions in the pineal region, especially ependymoma and choroid plexus papilloma.	73%	75% times	No specific imaging findings	Well-circumscribed lesions with variable signal intensity on T1-weighted images, high signal intensity on T2-weighted images, and enhancement on postcontrast images. Cystic areas are commonly present. Hyperintensity on T1-weighted images has been described, which is hypothesized to be related to secretory inclusions containing protein or glycoprotein.
Germinoma	Grade II	Account for 1%–2% of all cranial neoplasms 65% of intracranial germinomas occur in the pineal region	>79%	The possibility of CSF seeding necessitates imaging evaluation of the entire neuroaxis	Sharply circumscribed, hyperattenuating mass that engulfs the pineal calcifications	Demonstrates a solid mass that may have cystic components. Germinomas are iso- to hyperintense to gray matter on T1- and T2-weighted images Avid, homogeneous enhancement on postcontrast images
Teratoma	Grade III	Mature teratoma reveals a lobulated neoplasm with a complex mixture of adult-type tissues from all three embryonic germ layers. Skin and skin appendages may be seen due to the ectodermal component. The mesoderm contributes to the presence of cartilage, bone, fat, and smooth and skeletal muscle. Respiratory or enteric epithelium arises from the endodermal component. Immature teratomas contain incompletely differentiated tissue elements that resemble fetal tissue.			Multiloculated, lobulated lesion with foci of fat attenuation, calcification, and cystic regions	T1-weighted MR images may show foci of T1 shortening due to fat and variable signal intensity related to calcification. On T2-weighted images, the soft-tissue component is iso- to hypointense.
Pineal Cyst	Grade II	Pineal cysts occur in all age ranges but are most predominant in adults 40–49 years of age; studies demonstrate a female predominance. Their origin is debated, with some suggesting they result from degenerative changes in the gland. These lesions are typically asymptomatic and are usually 2–15 mm in size. Follow-up studies have indicated that these lesions remain stable in size over time. When they exceed 15 mm, patients may become symptomatic, typically with headache or visual changes. Intracystic hemorrhage (“pineal apoplexy”) and acute hydrocephalus rarely occur; resultant death has been reported	75% of pineal cysts remained stable during a period of 0.5–9.1 years.	Rare	No specific imaging findings	Round or oval, thin-walled, and well-circumscribed. They typically demonstrate signal intensity similar to that of CSF on T1- and T2-weighted images
Epidermoid and Dermoid Cysts	Grade II III	The wall of epidermoid cysts is composed of simple stratified squamous epithelium, and the cyst contents consist of layers of keratinaceous debris, which impart a “pearly” appearance to the gross specimen. Dermoid cysts contain dermal appendages (hair follicles, sweat glands. Both lesions slowly expand over time and rupture can result in chemical meningitis, which may be fatal.	N/A	N/A	Epidermoid cysts have low attenuation, similar to that of CSF. Dermoid cysts have a more variable appearance, and areas of low attenuation may be seen due to a lipid component—not due to fat, which is of mesodermal origin. Peripheral calcifications may be seen in both lesions.	Epidermoid cysts are hypointense on T1-weighted images and hyperintense on T2-weighted images, with signal intensity similar to that of CSF. They insinuate into adjacent structures and encase nerves and blood vessels, making resection difficult.
Astrocytoma	Grade I II III IV	Uncommon. They derive from stromal astrocytes In the pineal region they arise from the splenium of the corpus callosum, the thalamus, or the tectum of the midbrain. Rarely, they may arise from the neuronal elements within the pineal gland.	Grade 2 34% without treatment 70% with radiation therapy The prognosis is worst for these grade 4 gliomas. Few patients survive beyond 3 years.	Uncommon	In low grade astrocytoma: Poorly demarcated mass Low density No inhancement inside the tumor In few cases we might see some calcification and cystic changes inside the mass In high grade astrocytoma: Poorly demarcated mass Low density There are partial enhancement inside the tumor mass	Bulbous enlargement of the tectal plate is noted. The lesion is typically isointense on T1-weighted images Hyperintense on T2-weighted images with no to minimal enhancement on postcontrast images
Lipoma	No Grading	Abnormal differentiation of the meninx primitiva, which is the undifferentiated mesenchyme that surrounds the developing brain and normally develops into the leptomeninges and subarachnoid space. Lipomas represent malformations and not neoplasms. Blood vessels and nerves course through them, making resection difficult if required.	Malignant transformation of lipomas into liposarcomas is very rare Liposarcomas are not produced from pre-existing benign lesions	Uncommon	Low attenuation, consistent with fat	hyperintense on T1-weighted images with saturation on fat-saturated images

References

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