Pineocytoma Pathophysiology

# Overview
The exact pathogenesis of  is not fully understood.
OR
It is thought that  is the result of / is mediated by / is produced by / is caused by either , , or .
OR
 is usually transmitted via the  route to the human host.
OR
Following transmission/ingestion, the  uses the  to invade the  cell.
OR
 arises from s, which are  cells that are normally involved in .
OR
The progression to  usually involves the .
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The pathophysiology of  depends on the histological subtype.

# Pathophysiology

## Physiology
The normal physiology of  can be understood as follows:

## Pathogenesis
- The exact pathogenesis of  is not completely understood.
OR
- It is understood that  is the result of / is mediated by / is produced by / is caused by either , , or .
-  is usually transmitted via the  route to the human host.
- Following transmission/ingestion, the  uses the  to invade the  cell.
-  arises from s, which are  cells that are normally involved in .
- The progression to  usually involves the .
- The pathophysiology of  depends on the histological subtype.

# Genetics
 is transmitted in  pattern.
OR
Genes involved in the pathogenesis of  include:
OR
The development of  is the result of multiple genetic mutations such as:

# Associated Conditions
Conditions associated with  include:

# Gross Pathology
On gross pathology, , , and  are characteristic findings of .

# Microscopic Pathology
On microscopic histopathological analysis, , , and  are characteristic findings of .

# Pathophysiology

## 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.
- 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 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.
- 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.
- 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.

## Gross Pathology
On gross pathology, pineocytoma is characterized by solid, sometimes with focal areas of cystic change, gray, well-circumscribed mass with or without hemorrhage.

## Microscopic Pathology
On microscopic histopathological analysis, pineocytoma is characterized by:
- Cytologically benign cells (uniform size of nuclei, regular nuclear membrane, light chromatin)
- Pineocytomatous/neurocytic rosette, which is an irregular circular/flower-like arrangement of cells with a large meshwork of fibers (neuropil) at the center.

## Immunohistochemistry
Pineocytoma is demonstrated by positivity to tumor markers such as:
- Synaptophysin
- Neuron-specific enolase
- GFAP
- Chromogranin A
- PLAP
- Ki-67
- Beta tubulin III