MICROSCOPIC DESCRIPTION: Sections show a thinly encapsulated tumour composed of nests and trabeculae of polygonal cells in a stroma with prominent small vessels. The cells have round to oval nuclei, fine chromatin, inconspicuous nucleoli and a moderate amount of vacuolated eosinophilic cytoplasm. Scattered bizarre cells are noted. Mitoses are not a feature. No necrosis is seen. By immunohistochemistry the tumour cells are CD56, synaptophysin and chromogranin positive. Staining for S100 highlights sustentacular cells.
DIAGNOSIS: Lesion, site unstated: Paraganglioma.