Protoplasmic astrocytoma: Difference between revisions

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===Microscopic Pathology===
===Microscopic Pathology===
*On microscopic histopathological analysis, protoplasmic astrocytoma is characterized by:
*On microscopic histopathological analysis, protoplasmic astrocytoma is characterized by:<ref name="pmid7785654">&lt;/nowiki&gt;{{cite journal| author=Prayson RA, Estes ML| title=Protoplasmic astrocytoma. A clinicopathologic study of 16 tumors. | journal=Am J Clin Pathol | year= 1995 | volume= 103 | issue= 6 | pages= 705-9 | pmid=7785654 | doi=10.1093/ajcp/103.6.705 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7785654  }}
</ref>
 
::*Scant cytoplasm
::*Scant cytoplasm
::*Rounded prominent nuclear contour
::*Rounded prominent nuclear contour
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:*Mucinous fluid containing microcystic spaces (prominent feature)
:*Mucinous fluid containing microcystic spaces (prominent feature)
:*Abscence of [[mitoses]], microvascular proliferation, and [[necrosis]]
:*Abscence of [[mitoses]], microvascular proliferation, and [[necrosis]]
:*temporal and frontal lobes were the most likely site of origin.<ref name="pmid7785654"></nowiki>{{cite journal| author=Prayson RA, Estes ML| title=Protoplasmic astrocytoma. A clinicopathologic study of 16 tumors. | journal=Am J Clin Pathol | year= 1995 | volume= 103 | issue= 6 | pages= 705-9 | pmid=7785654 | doi=10.1093/ajcp/103.6.705 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7785654  }}
:*temporal and frontal lobes were the most likely site of origin.
</ref>


===Immunohistochemistry===
===Immunohistochemistry===

Revision as of 20:57, 24 July 2019

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

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

Microscopic Pathology

  • On microscopic histopathological analysis, protoplasmic astrocytoma is characterized by:[1]
  • 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:

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.[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.[2]
  • Protoplasmic astrocytoma is a slow growing tumor with an indolent course.

Complications

  • Common complication of protoplasmic astrocytoma include:[2]

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:[2]

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:[3]
  • 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.[4]
  • Brain MRI is helpful in the diagnosis of protoplasmic astrocytoma. On MRI, protoplasmic astrocytoma is characterized by:[3][5]
MRI component Findings

T1

  • Hypointense compared to white matter

T2

  • Hyperintense compared to white matter

Fluid-attenuated inversion recovery (FLAIR)

  • Large areas of T2 hyperintensity suppress on FLAIR
  • These are not macrocystic, but rather represent the areas with abundant microcystic change

T1 with contrast

  • Little or no enhancement

Diffusion weighted imaging (DWI)

  • No restricted diffusion

Other Imaging Findings

Magnetic Resonance Spectroscopy

Magnetic Resonance Perfusion

  • MR perfusion may be helpful in the diagnosis of protoplasmic astrocytoma, which demonstrates no elevation of relative cerebral blood volume (rCBV).[3]


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.[6]

Treatment

Medical Therapy

References

  1. 1.0 1.1 </nowiki>Prayson RA, Estes ML (1995). "Protoplasmic astrocytoma. A clinicopathologic study of 16 tumors". Am J Clin Pathol. 103 (6): 705–9. doi:10.1093/ajcp/103.6.705. PMID 7785654.
  2. 2.0 2.1 2.2 Clinical presentation of protoplasmic astrocytoma. Dr Bruno Di Muzio and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/protoplasmic-astrocytoma. Accessed on January 8, 2016
  3. 3.0 3.1 3.2 3.3 Radiological features of protoplasmic astrocytoma. Dr Bruno Di Muzio and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/protoplasmic-astrocytoma. Accessed on January 8, 2016
  4. Tay KL, Tsui A, Phal PM, Drummond KJ, Tress BM (2011). "MR imaging characteristics of protoplasmic astrocytomas". Neuroradiology. 53 (6): 405–11. doi:10.1007/s00234-010-0741-2. PMID 20644924.
  5. Radiographic features of low grade infiltrative astrocytoma. Dr Ahmed Abd Rabou and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/low-grade-infiltrative-astrocytoma. Accessed on January 8, 2016
  6. Radiographic features of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016

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