Acoustic neuroma classification
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Acoustic neuroma may be classified into several subtypes based on MRI scan, microscopic histopathology, and whether or not they are associated with neurofibromatosis type 2. Acoustic neuroma may be classified based on MRI scan into three subtypes: entirely canalicular, intracranial extension without brainstem distortion, and intracranial extension with brain stem distortion. Based on microscopic histopathology, acoustic neuroma may be classified into four subtypes: conventional schwannoma, cellular schwannoma, plexiform schwannoma, and melanotic schwannoma.
Acoustic neuroma may be classified into two subtypes, based on whether or not they are associated with neurofibromatosis type 2.
- Sporadic: The vast majority are the sporadic form. Ninety five % of all cases of acoustic neuroma are sporadic. The cause of sporadic form is unclear.
- Acoustic neuroma associated with neurofibromatosis type II (NF2). NF2 is a rare disorder and it accounts for 5% of acoustic neuromas.
Based on the MRI scan, acoustic neuromas can be classified into three subtypes:
- Entirely intracanalicular: The entire tumor is completely within the bony canal
- Intracranial extension without brain stem distortion: intracranial portion of the tumor is 1-2 cm.
- Intracranial extension with brain stem distortion: intracranial portion of the tumor is greater than 2 cm.
- Conventional schwannoma: It is the most common schwannoma.
- Cellular schwannoma: It may mimic malignant peripheral nerve sheath tumor.
- Plexiform schwannoma: It may mimic malignant peripheral nerve sheath tumor if cellular- especially in childhood.
- Melanotic schwannoma: It may be confused with melanoma.
It is associated with psammomatous form (psammomatous melanotic schwannoma) and with a heritable disorder (Carney complex). The Carney complex, also known as Carney syndrome, NAME syndrome and LAMB syndrome, is an autosomal dominant syndrome associated with endocrinopathy, endocrine and nonendocrine tumors, and spotty pigmentation of the skin including the following:
- Schwannoma. Librepathology(2015) http://librepathology.org/wiki/index.php/Schwannoma Accessed on October 2 2015
- Kurtkaya-Yapicier O, Scheithauer B, Woodruff JM (2003). "The pathobiologic spectrum of Schwannomas.". Histol Histopathol. 18 (3): 925–34. PMID 12792904.