Protoplasmic astrocytoma
Synonyms and keywords: Protoplasmic astrocytomas; Diffuse astrocytoma; Low grade astrocytoma

# Overview
Protoplasmic astrocytoma is a rare variant of diffuse low grade astrocytoma with characteristic histological and imaging features. It has been suggested that protoplasmic astrocytoma represents a variant of dysembryoplastic neuroepithelial tumors (DNET), as they share histologic and imaging features. Currently, protoplasmic astrocytoma is classified as a subtype of diffuse low-grade astrocytoma. The possibility that a primary cerebral neoplasm represents a protoplasmic astrocytoma should be considered in a patient with a large frontal or temporal tumor that has a very high signal on T2 with a large proportion of the tumor showing substantial T2 FLAIR suppression.

# Classification
Protoplasmic astrocytoma is a subtype of astrocytoma and is included in the classification of astrocytoma. For more information about the classification of astrocytoma, click here.

# Pathophysiology

## Gross Pathology
- Protoplasmic astrocytoma appear to have a predilection for the frontal and temporal lobes.

## Microscopic Pathology
- On microscopic histopathological analysis, protoplasmic astrocytoma is characterized by:
- Scant cytoplasm
- Rounded prominent nuclear contour
- Flaccid processes
- Low cellular density
- Mild nuclear atypia (enlarged, irregular contour, hyperchromasia, and coarsened nuclear chromatin pattern)
- Mucinous fluid containing microcystic spaces (prominent feature)
- Abscence of mitoses, microvascular proliferation, and necrosis
- temporal and frontal lobes were the most likely site of origin.

## Immunohistochemistry
- Protoplasmic astrocytoma is demonstrated by positivity to tumor marker such as GFAP.

# Causes
There are no causes for protoplasmic astrocytoma.

# Differentiating Protoplasmic Astrocytoma from other Diseases
- Protoplasmic astrocytoma must be differentiated from:
- Gemistocytic astrocytoma
- Oligoastrocytoma
- Stroke
- Cerebritis
- Herpes simplex encephalitis
- Anaplastic astrocytoma
- Oligodendroglioma
- Angiocentric glioma

# Epidemiology and Demographics

## Age
- Protoplasmic astrocytoma is a rare disease that tends to affect young adults.
- The mean age at diagnosis is 32 years.

## Gender
- Males are more commonly affected with protoplasmic astrocytoma than females. The male to female ratio is approximately 1.67 to 1.

# Risk Factors
There are no established risk factors for protoplasmic astrocytoma.

# Screening
There is insufficient evidence to recommend routine screening for protoplasmic astrocytoma.

# Natural History, Complications and Prognosis

## Natural History
- If left untreated, patients with protoplasmic astrocytoma may progress to develop seizures, focal neurological deficits, and hydrocephalus.
- Protoplasmic astrocytoma is a slow growing tumor with an indolent course.

## Complications
- Common complication of protoplasmic astrocytoma include:
- Hydrocephalus

# Diagnosis

## Diagnostic Study of Choice
The diagnosis of protoplasmic astrocytoma is based on a tissue biopsy.

## History and Symptoms
- When evaluating a patient for protoplasmic astrocytoma, you should take a detailed history of the presenting symptom (onset, duration, and progression), other associated symptoms, and a thorough family and past medical history review.
- Symptoms of protoplasmic astrocytoma include:
- Headaches
- Seizures
- Changes in mood
- Hemiparesis
- Changes in personality
- Changes in vision
- Speech difficulties

## Physical Examination
Patients with protoplasmic astrocytoma usually appear

## Laboratory Findings
There are no diagnostic laboratory findings associated with protoplasmic astrocytoma.

## Electrocardiogram
There are no ECG findings associated with protoplasmic astrocytoma.

## X-ray
There are no x-ray findings associated with protoplasmic astrocytoma.

## Echocardiography or Ultrasound
There are no echocardiography/ultrasound findings associated with protoplasmic astrocytoma.

## CT scan
- Head CT scan is helpful in the diagnosis of protoplasmic astrocytoma. On CT scan, protoplasmic astrocytoma is characterized by:
- Hypodense mass
- Positive mass effect
- No enhancement
- Cystic or fluid attenuation, due to the aforementioned prominent mucinous microcystic component

## MRI
- The possibility that a primary cerebral neoplasm represents a protoplasmic astrocytoma should be considered in a patient with a large frontal or temporal tumor that has a very high signal on T2 with a large proportion of the tumor showing substantial T2 FLAIR suppression.
- Brain MRI is helpful in the diagnosis of protoplasmic astrocytoma. On MRI, protoplasmic astrocytoma is characterized by:

## Other Imaging Findings

### Magnetic Resonance Spectroscopy
- MR spectroscopy may be helpful in the diagnosis of protoplasmic astrocytoma, which demonstrates elevated choline/creatine ratio.

### Magnetic Resonance Perfusion
- MR perfusion may be helpful in the diagnosis of protoplasmic astrocytoma, which demonstrates no elevation of relative cerebral blood volume (rCBV).

## Other Diagnostic Studies

### Electroencephalogram
- Electroencephalogram (EEG) is performed in cases of protoplasmic astrocytoma to record the continuous electrical activity of the brain and locate the seizure activity.

# Treatment

## Medical Therapy
There is no specific chemotherapy regimen for protoplasmic astrocytoma. It is managed as an astrocytoma.
- Post surgical medical therapy is recommended in all patients with astrocytoma tumor.

## Astrocytoma
- 1 Grade 1 and 2 - Low grade astrocytomas
1.1 Wait and see
The wait and see approach is for young patient with complete or nearly complete tumor resection.
since the low grade astrocytoma will finally grow to high grade astrocytoma, we should screen these patients with contrast MRI every 4 month.
1.2 Radiation therapy
Immediate post surgery radiation therapy can reduce the progression rate.
It doesn't affect survival since it cannot prevent transformation of low grade astrocytoma to high grade astrocytoma.
Preferred regimen: 50 t0 54 Gy
1.3 Adjunctive chemotherapy
1.3.1 Temozolomide
1.3.2 PVC (Procarbazine, Lomustine, Vincristine)
Based on previous studies, patients who get chemotherapy along with radiotherapy immediately after surgery has better outcome.
- 1.1 Wait and see
The wait and see approach is for young patient with complete or nearly complete tumor resection.
since the low grade astrocytoma will finally grow to high grade astrocytoma, we should screen these patients with contrast MRI every 4 month.
- The wait and see approach is for young patient with complete or nearly complete tumor resection.
- since the low grade astrocytoma will finally grow to high grade astrocytoma, we should screen these patients with contrast MRI every 4 month.
- 1.2 Radiation therapy
Immediate post surgery radiation therapy can reduce the progression rate.
It doesn't affect survival since it cannot prevent transformation of low grade astrocytoma to high grade astrocytoma.
Preferred regimen: 50 t0 54 Gy
- Immediate post surgery radiation therapy can reduce the progression rate.
- It doesn't affect survival since it cannot prevent transformation of low grade astrocytoma to high grade astrocytoma.
- Preferred regimen: 50 t0 54 Gy
- 1.3 Adjunctive chemotherapy
1.3.1 Temozolomide
1.3.2 PVC (Procarbazine, Lomustine, Vincristine)
Based on previous studies, patients who get chemotherapy along with radiotherapy immediately after surgery has better outcome.
- 1.3.1 Temozolomide
- 1.3.2 PVC (Procarbazine, Lomustine, Vincristine)
- Based on previous studies, patients who get chemotherapy along with radiotherapy immediately after surgery has better outcome.
- 2 Grade 3 - Anaplastic astrocytoma
2.1 Radiotherapy+ chemotherapy (Temozolomide)
Studies demonstrated that the combination of radiotherapy and chemotherapy with temozolomide is more effective.
2.2 Radiation
2.3 Chemotherapy
2.3.1 Procarbazine, Lomustine, Vincristine
2.3.2 Procarbazine, Lomustine, Temozolomide
- 2.1 Radiotherapy+ chemotherapy (Temozolomide)
Studies demonstrated that the combination of radiotherapy and chemotherapy with temozolomide is more effective.
- Studies demonstrated that the combination of radiotherapy and chemotherapy with temozolomide is more effective.
- 2.2 Radiation
- 2.3 Chemotherapy
2.3.1 Procarbazine, Lomustine, Vincristine
2.3.2 Procarbazine, Lomustine, Temozolomide
- 2.3.1 Procarbazine, Lomustine, Vincristine
- 2.3.2 Procarbazine, Lomustine, Temozolomide
- 3 Grade 4 - Glioblastoma multiform
3.1 Chemotherapy ( radiotherapy)
3.1.1 Temozolomide
3.2 Bevacizumab
A monoclonal antibody which bind to VEGF and inactivate it.
3.3 Alternating electric fields
A portable device which will be placed on the scalp for generating TT fields. The combination of this device with Temozolomide will significantly increase survival.
3.4 Carmustine polymer wafers
Implanted at the time of surgery.
Can be used in combination with chemotherapy or radiation.
- 3.1 Chemotherapy ( radiotherapy)
3.1.1 Temozolomide
- 3.1.1 Temozolomide
- 3.2 Bevacizumab
A monoclonal antibody which bind to VEGF and inactivate it.
- A monoclonal antibody which bind to VEGF and inactivate it.
- 3.3 Alternating electric fields
A portable device which will be placed on the scalp for generating TT fields. The combination of this device with Temozolomide will significantly increase survival.
- A portable device which will be placed on the scalp for generating TT fields. The combination of this device with Temozolomide will significantly increase survival.
- 3.4 Carmustine polymer wafers
Implanted at the time of surgery.
Can be used in combination with chemotherapy or radiation.
- Implanted at the time of surgery.
- Can be used in combination with chemotherapy or radiation.