Question:medium
Which of the following is the most characteristic ultrastructural feature of paraganglioma on electron microscopy?
Which of the following is the most characteristic ultrastructural feature of paraganglioma on electron microscopy?
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Neuroendocrine cells store catecholamines in membrane-bound granules with a dark centre.
Updated On: Jun 24, 2026
- Shrunken mitochondria
- Large Golgi apparatus
- Frequent mitoses
- Dense core neuroendocrine granules
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The Correct Option is D
Solution and Explanation
A paraganglioma comes from neuroendocrine tissue, the same cell line that makes and releases catecholamines. The key question is what such a cell looks like at very high magnification.
Hormone-secreting neuroendocrine cells package their product into small round vesicles bounded by a membrane. The core of each vesicle is packed with electron-opaque material, so it appears dark and is named a dense-core granule. When a pathologist sees plentiful dense-core granules on EM, it confirms the tumour is neuroendocrine in nature, and a paraganglioma fits this picture exactly.
Now rule out the distractors. Mitochondrial shrinkage is a degenerative or artefactual change and points to no specific diagnosis. A prominent Golgi simply means active secretion in general and is not unique to paraganglioma. Counting mitoses is a light-microscopy proliferation index and tells you nothing about ultrastructure or cell origin.
The single ultrastructural detail that brands a tumour as a paraganglioma is therefore the secretory granule with a dense centre.
\[\boxed{\text{Dense core neuroendocrine granules}}\]
Hormone-secreting neuroendocrine cells package their product into small round vesicles bounded by a membrane. The core of each vesicle is packed with electron-opaque material, so it appears dark and is named a dense-core granule. When a pathologist sees plentiful dense-core granules on EM, it confirms the tumour is neuroendocrine in nature, and a paraganglioma fits this picture exactly.
Now rule out the distractors. Mitochondrial shrinkage is a degenerative or artefactual change and points to no specific diagnosis. A prominent Golgi simply means active secretion in general and is not unique to paraganglioma. Counting mitoses is a light-microscopy proliferation index and tells you nothing about ultrastructure or cell origin.
The single ultrastructural detail that brands a tumour as a paraganglioma is therefore the secretory granule with a dense centre.
\[\boxed{\text{Dense core neuroendocrine granules}}\]
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