Comparison study of clinicopathological features of cellular schwannoma between retroperitoneum and other sites

Cellular schwannoma (CS) is a relatively rare neural tumor with few reports. This study aimed to compare the clinicopathological characteristics of CS in the retroperitoneum and other sites by analyzing the hematoxylin-eosin (HE) staining and immunohistochemical (IHC) staining results, to provide some help for pathological diagnosis.

A total of 79 CS cases from the Department of Pathology, Peking University International Hospital were collected, and the diagnosis was based on the 5^th WHO classification of soft tissue tumors. The staining results of HE and IHC were judged and analyzed according to the instructions. The t-tests, Chi-square test and Fisher's exact probability test were used for statistical analysis.

Compared with other sites, the volume of retroperitoneal CS tumors were larger (t=4.265, P=0.001) and more likely to recur (χ²=4.223, P=0.04). Nerve sheath structures were rare around the tumors (χ²=60.096, P=0.000). Immunohistochemically, there was a difference in the expression of glial fibrillary acidic protein (GFAP), Cytokeratin (CK), and myelin basic protein (MBP) between the two groups (χ²=54.290, P=0.000; χ²=4.879, P=0.027; χ²=31.792, P=0.000). But there was no difference in expression between the two groups in the other indexes.

It founded that Retroperitoneal CS was often positive for GFAP and CK, suggesting it originated from unmyelinated Schwann cells. CS in other sites, the expression of GFAP and CK was often negative, indicating they derived from myelinated Schwann cells. The expression of MBP in the peripheral nerve sheath structure of CS can be used to determine whether the tumor originates from myelinated or unmyelinated Schwann cells. These findings may provide a reference for revealing pathogenesis, diagnosis and evaluating prognosis of CS.