Zellballen

Nest-like clusters of uniform, round-to-polygonal chief cells surrounded by delicate richly vascular tissue and sustentacular cells, a pattern characteristic of paraganglioma
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In the jugulotympanic paraganglioma, nests and trabeculae are composed of small to medium-sized cells with ovoid nuclei and abundant pink cytoplasm within a rich vascular network, characteristic of the Zellballen pattern (hematoxylin and eosin, original magnification x20).
Sections of the carotid mass showed Zellballen architecture type I cells (Figure 11, B) that were positive for neuron-specific enolase (Figure 11, C), chromogranin (Figure 11, D), and synaptophysin (Figure 11, E).
The tumour had a Zellballen pattern with low cellularity, with the absence of comedonecrosis, lymphovascular invasion, or high Ki-67.
Histopathological analysis of tissue sections of the adrenal mass yielded an unexpected result: a pheochromocytoma was diagnosed on the basis of typical well-arranged nests called zellballen.
The presence of typical Zellballen pattern of arrangement of tumour cells surrounded by sustentacular cells and fibrovascular stroma favour a diagnosis of pheochromocytoma (Fig.
Neoplastic chief cells are arranged in a nested/organoid/ zellballen pattern along intervening fibrovascular septae.
The tumor in our case was diagnosed as PPP due to the observation of a diffuse zellballen pattern throughout the tumor, the absence of classic carcinoid tumor architecture, the presence of distinctive cytoplasmic vacuoles, a negative immunohistochemical staining for cytokeratin.
Chief cells are arranged in a characteristic pesudoalveolar pattern described as Zellballen (which means cells balls).
11] Our immunohistochemical analysis revealed that the tumor was positive for Chromogranin A, S-100, cytokeratin negative and Ki67 index <2% with a characteristic zellballen pattern on histopathology, thus providing a basis for a correct diagnosis of nonchromaffin paraganglioma of the retroperitoneum in the patient arising from pancreas.
The chief cells are characteristically packed in a Zellballen pattern, separated by a fibrovascular stroma and surrounded by the more basophilic sustentacular cells.