Clinicopathological differences between classical schwannomas and cellular schwannomas in the retroperitoneum.

This study aimed to compare clinical and pathological features of retroperitoneal classical schwannomas and cellular schwannomas. A total of 64 cases of retroperitoneal classical schwannoma and 48 cases of cellular schwannoma were studied. Histopathological analysis was performed using hematoxylin and eosin staining and immunohistochemistry. Retroperitoneal cellular schwannomas exhibited 100% (48/48) and 75% (36/48) positive expression for glial fibrillary acidic protein (GFAP) and cytokeratins (CK), respectively. Classical schwannomas showed rates of 6.25% (4/64) and 15.63% (10/64), respectively (P < .05). In classic schwannomas, 85.9% (55/64) showed a reticular pattern of positive anti-CD34 staining around tumor margins and subcapsular areas vs 52.1% (25/48) in cellular schwannomas (P < .05). Cellular schwannomas exhibited more mitotic figures than classical schwannoma (P < .05). The recurrence rate of cellular schwannomas was 10.42% (5/48), while that of classical schwannomas was 1.56% (1/64) (P < .05). Retroperitoneal cellular schwannomas commonly express GFAP and CK compared to classical schwannomas, suggesting that cellular schwannoma may originate from unmyelinated Schwann cells, while classical schwannoma may originate from myelinated Schwann cells. Anti-CD34 staining patterns may be used to distinguish between the 2 types. Retroperitoneal cellular schwannomas also show higher mitotic activity and are more prone to recurrence.