Schwann cell tumour. Light micrograph of a section through a schwannoma, a benign (non-cancerous) tumour of Schwann cells, the protective sheaths of peripheral nerve fibres. Two patterns of tumour growth are seen in this specimen; Antoni type A and Antoni type B. The Antoni type A areas (dark purple at top of frame) are densely packed with cells that are arranged in whorls. The Antoni type B areas (lighter purple at bottom right) show cell loss.