Adrenal gland and paraganglia
Pheochromocytoma / paraganglioma

Author: Lan L. Gellert, M.D., Ph.D. (see Authors page)
Editorial Board Member Review: Debra Zynger, M.D. (see Authors page)

Revised: 17 August 2017, last major update August 2017

Copyright: (c) 2002-2017,, Inc.

PubMed Search: Paraganglioma [title]

Related topics: Aorticopulmonary, Carotid body, Cauda equina, Jugulotympanic, Laryngeal, Pigmented
Cite this page: Gellert, L. L. Paraganglioma. website. Accessed July 20th, 2018.
Definition / general
  • Tumors of paraganglia, regardless of location (although tumor of adrenal medulla is termed pheochromocytoma)
  • Histologically similar, regardless of location
Essential features
  • Chemodectoma refers to carotid and aortic body paraganglioma (tumors of paraganglia with a chemoreceptor function)
  • Average patient age is fourth and fifth decade
  • The distribution by gender is almost equal
  • Tumor mostly distributed along parasympathetic nerves, sympathetic chains and nerves
  • Other sites include orbit, ear, nasopharyngeal, gangliocytic and cauda equine
Clinical features
  • Non symptomatic, hypertension or local compression
Prognostic factors
  • Determined to be malignant only when metastases are present
  • Site: organ of Zuckerkandl (22% - 50% malignant vs. 10%+ in adrenal gland)
Case reports
  • Surgical excision
Gross description
  • Rubbery, firm, may have pseudocapsule
  • Brown cut surface; variable central scar
Gross images

Images hosted on Pathout server, contributed by. Dr. Debra Zynger, Ohio State University (USA):
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Parapharyngeal paraganglioma

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Bladder paraganglioma

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Retroperitoneal paraganglioma

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Retroperitoneal tumor

Microscopic (histologic) description
  • Similar to pheochromocytoma
  • Nesting (zellballen) or trabecular pattern of cells within a prominent vascular network
  • Zellballen pattern may be obscured by anastomosing bands
  • Round / oval cells and giant multinucleated cells with abundant granular eosinophilic or basophilic cytoplasm
  • May have nuclear atypia and vascular invasion (does not indicate malignancy)
  • May have dysmorphic vessels, melanin-like pigment, abundant stroma and osseous metaplasia
  • Intracytoplasmic hyaline globules are present in sympathoadrenal paragangliomas
  • No or rare mitotic figures except in obviously malignant tumors; no rosettes or acini
  • Usually no chronic inflammatory infiltrate, no necrosis (unless preoperative tumor embolization)
Microscopic (histologic) images

Images hosted on PathOut server:

Images contributed by Lan L. Gellert, M.D., Ph.D.

Abdominal paraganglioma

Ear paraganglioma

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Vagal paraganglioma

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Various images

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Encapsulated mass with zellballen pattern

Cytology description
  • Irregular clusters of tumor cells with eosinophilic finely granular cytoplasm and mildly irregular nuclei
  • May have marked cytologic atypia
  • Fine needle aspiration not recommended for carotid body paragangliomas due to high likelihood of misinterpretation and risk for catecholamine crisis and hemorrhage
Positive stains
Electron microscopy description
  • Chief cells have abundant cytoplasmic neurosecretory granules
  • May have giant mitochondria with paracrystalline inclusions
  • Sustentacular cells wrap around chief cells and lack neurosecretory granules
  • No desmosomes
Differential diagnosis
Board review question #1
Which of the following histologic features of paraganglioma is predictive of malignant behavior?

  1. Capsular invasion
  2. Cytologic atypia
  3. Increased mitosis
  4. Lymphovascular invasion
  5. None of the above
Board review answer #1
E. Paraganglioma is determined to be malignant only when metastases are present