This image shows Antoni A areas with nuclear palisading and Verocay bodies and occasional benign glandular elements. These are not entrapped normal structures but represent true epithelial differentiation within the tumor.
About the Disease
Schwannoma is a slow-growing, encapsulated benign peripheral nerve sheath tumor that is usually seen sporadically (90% of cases). The remainder are associated with Neurofibromatosis 2 (3%), schwannomatosis (2%), or multiple meningiomas with or without NF2 (5%). Schwannomas may rarely arise in the setting of NF1. The most common locations are head, neck, upper and lower extremities, posterior mediastinum, and retroperitoneum. The cut surface is yellow-white or gray. Secondary changes such as hemorrhage, cystic change, cytologic atypia, and calcification are more frequent in the larger deep-seated tumors. Schwannomas are composed of cellular Antoni A areas alternating with hypocellular Antoni B areas. Schwann cells in Antoni A areas show nuclear palisading, whorling patterns, and Verocay bodies. Antoni B areas consist of spindle cells in a loose myxoid or hyalinized stroma, inflammatory cells, collagen fibers, and ectatic deformed vessels with hyalinized walls and thrombi. Schwann cells consistently show positivity for S-100 and SOX10. Cellular schwannoma is composed of mainly Antoni A areas and shows increased mitotic activity (usually < 4 mitoses/10 HPF). They are usually found in deep-seated locations and behave in a benign fashion. Plexiform schwannomas are superficial and multinodular and make up about 5% of all schwannomas. The linkage to Neurofibromatosis 1 or 2 is weak, unlike the strong association between plexiform neurofibroma and NF1. References: 1) Enzinger & Weiss's Soft Tissue Tumors, Sixth Edition, 2014; p. 813-829.