Lung tumor
Benign tumors
Paraganglioma

Author: Roseann Wu, M.D. (see Authors page)

Revised: 31 December 2015, last major update December 2015

Copyright: (c) 2003-2015, PathologyOutlines.com, Inc.

PubMed Search: Paraganglioma [title] lung
Definition / General
  • Very rare neuroendocrine tumor in lung
  • Usually benign
  • Metastases to lung are more common than a lung primary
Essential Features
  • Classic "zellballen" / organoid pattern with S100+ sustentacular cells, similar to pheochromocytoma
  • Primary pulmonary paraganglioma is extremely rare and requires ancillary studies to differentiate from carcinoid tumor
  • Considered malignant if metastasis is demonstrated
Terminology
Epidemiology
  • Extremely rare (< 25 case reports)
  • Thoracic paragangliomas comprise 1 - 2% of all paragangliomas (including pheochromocytomas)
  • Middle aged males predominate in sporadic cases, but middle aged females predominate in MEN 2 syndromes and present earlier
Sites
  • Various organs
  • Thoracic paragangliomas mostly in mediastinal compartment but can also be primary intrapulmonary mass
  • Rarely may be endobronchial
Etiology
  • Arise from paraganglion cells; neural crest origin
  • Intrapulmonary paragangliomas may arise from paraganglia-like structures in interstitium
Clinical Features
  • Mostly asymptomatic or non-specific symptoms
  • Obstructive symptoms if endobronchial
  • May show symptoms depending on specific neuropeptide production, if functional (i.e. hypertension from elevated norepinephrine)
  • May invade bronchus and metastasize to lymph nodes
Diagnosis
  • Usually solitary nodules discovered incidentally
  • Diagnosis requires histologic examination with ancillary studies
Laboratory
  • May show elevated serum levels of specific neuropeptide
Radiology Description
  • Xray: abnormal lung shadow
  • CT: well circumscribed to slightly irregular, solid mass
  • PET scan: may show FDG avid mass
Prognostic Factors
  • Mostly benign behavior
  • If metastases, call "malignant paraganglioma", which may show reduced sustentacular cells and decreased neuropeptide markers
  • Features most predictive of malignancy: extra-adrenal location, coarse nodularity of tumor, confluent tumor necrosis, absence of hyaline globules (Hum Pathol 1990;21:1168)
Case Reports
Treatment
  • Surgical resection (local excision or lobectomy)
Clinical Images
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Pulmonary nodule

Gross Description
  • Solitary or multiple, usually peripheral mass, often microscopic but may be several centimeters
  • Round to lobulated, well circumscribed but may show infiltrating border
  • Grey, pink, tan to orange color, may show areas of hemorrhage
Gross Images
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Bulging mass

Micro Description
  • Organoid, trabecular and alveolar patterns, variable "zellballen"
  • Zellballen pattern (nested islands of chief cells) with inconspicuous sustentacular cells and capillary network at periphery (Am J Surg Pathol 2004;28:825)
  • Variable nuclear size, some cells with pleomorphism or hyperchromasia
  • Round to oval nuclei, prominent nucleoli, clear to eosinophilic and finely granular cytoplasm
  • Nuclear pseudoinclusions, intercellular hyaline globules, spindle cell or oncocytic changes may be seen
  • Presence of mitoses and vascular invasion not helpful for distinguishing benign and malignant
  • Necrotic foci may be seen
  • May show partly infiltrating border of lymphocytes
Micro Images

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Carotid body tumor

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Histology of nodule

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Lung tumor cells

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S100

Cytology Description
  • Papillary-like clusters of epithelioid cells with round to oval nuclei, evenly dispersed chromatin, micronucleoli, occasional anisonucleosis (Acta Cytol 2001;45:459)
  • Abundant cells with round or oval nuclei and marked anisokaryosis with tendency to form acini or follicular structures
  • Binucleation and intranuclear cytoplasmic inclusions (Acta Cytol 1988;32:386)
Positive Stains
Negative Stains
Electron Microscopy Description
  • Dense core granules with internal, submembranous, eccentric halo emanating in a bubble-like fashion ("norepinephrine-type" granules)
Molecular / Cytogenetics Description
  • Mutations in RET gene on chromosome 10
Differential Diagnosis