Abstract
Meningiomas are common tumors of the central nervous system. Although their histological diagnosis is usually straightforward, their differential diagnosis versus other tumors may be challenging at times. The objective of this study is to assess the diagnostic value of CD13 immunoexpression in the differential diagnosis between meningiomas and their morphological mimics. Immunohistochemical analysis for CD13, epithelial membrane antigen, SOX10, and STAT6 was carried out in a large cohort of primary meningeal tumors comprising 225 meningiomas, 15 schwannomas, and 20 solitary fibrous tumor/hemangiopericytomas. Within the meningioma group, the expression of CD13 and epithelial membrane antigen was distinguished in three categories using a semiquantitative score. Most of meningiomas expressed CD13 (94%) and epithelial membrane antigen (96%) while none of the schwannomas nor of the solitary fibrous tumor/hemangiopericytomas was positive for either the two markers. Diffuse positivity for CD13 and epithelial membrane antigen was more common in low-grade meningiomas than in anaplastic ones, which were also more often negative for such markers, especially for CD13 (32%). CD13 is a helpful immunohistochemical marker for the differential diagnosis of meningiomas and their mimics, achieving in combination with epithelial membrane antigen maximal sensitivity (100%) and showing statistically relevant difference of expression in comparison with both schwannomas (p < 0.0001) and solitary fibrous tumor/hemangiopericytomas (p < 0.0001). Furthermore, loss of CD13 expression could be related to outcome as it is associated with worrisome histological findings, mainly in the setting of anaplastic meningiomas.
Highlights
Meningiomas are among the most common tumors of the central nervous system (CNS) in adults, accounting for 15–30% of primary intracranial tumors and for 25% of intraspinal ones [1]
According to World Health Organization (WHO) criteria, they are classified into fifteen histotypes and into three grades of malignancy, showing increasing recurrence risk: grade I meningiomas which are the most frequent and show a low risk of recurrence; grade II meningiomas, less common but displaying a higher rate of recurrence; grade III or malignant meningiomas, the rarest ones but associated with severe prognosis and poor overall survival [2]
Virchows Archiv diagnosis can be really challenging, as other tumors of the meninges may have a similar histological aspect: spinal cord schwannomas can be really close to meningiomas and meningeal solitary fibrous tumor/hemangiopericytomas (SFT/HPC), rare, may sometimes closely resemble fibrous and atypical meningiomas as well
Summary
Meningiomas are among the most common tumors of the central nervous system (CNS) in adults, accounting for 15–30% of primary intracranial tumors and for 25% of intraspinal ones [1]. Virchows Archiv diagnosis can be really challenging, as other tumors of the meninges may have a similar histological aspect: spinal cord schwannomas can be really close to meningiomas and meningeal solitary fibrous tumor/hemangiopericytomas (SFT/HPC), rare, may sometimes closely resemble fibrous and atypical meningiomas as well. In such cases, ancillary tests, like immunohistochemical exams, play a key role in sorting the diagnostic quandary out: meningothelial tumors are usually positive for epithelial membrane antigen (EMA) and progesterone receptors (PR), while schwannomas and SFT/HPCs commonly stain respectively positive for S100 and SOX10 and for CD34 and STAT6. In such circumstances, assessing the correct diagnosis can be extremely difficult
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