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Mediastinum

Other benign / low grade tumors

Paraganglioma

Reviewer: Hanni Gulwani, M.D. (see Reviewers page)
Revised: 2 March 2013, last major update December 2012
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.

General
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● Rare, 0.3% of mediastinal tumors

Epidemiology
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● Usually young women

Sites
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● Aorticopulmonary vascular root (anterosuperior mediastinum) or paravertebral (posterior mediastinum)

Aorticopulmonary:
● Mean 49 years old, no gender preference, 3% synthesize catecholamines
● May be fatal if extensive local invasion

Paravertebral:
● Mean 29 years old, usually men, 50% synthesize catecholamines
● Only rarely cause death

Clinical features
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● Associated with MEN II syndrome
● Also associated with Carney triad of pulmonary hamartomas, malignant gastrointestinal stromal tumors, extraadrenal paragangliomas

Diagnosis
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Catecholamine secreting tumors:
● Present with symptoms of pheochromocytoma, usually hypertension (abrupt; with tachycardia, palpitations, headaches, tremor, sense of apprehension, unresponsive to treatment; isolated paroxysmal episodes of hypertension in < 50%)
● Triad of sweating attacks, tachycardia and headaches is relatively specific

Catecholamine cardiomyopathy:
● Myocardial instability, ventricular arrhythmias
● Due to ischemic damage from vasoconstriction of coronaries or direct toxicity
● Myocytolysis, interstitial fibrosis, mononuclear inflammation

Diagnosis for catecholamine secreting tumors:
● Increased urinary excretion of catecholamines or metabolites (vanillylmandelic acid [VMA] or metanephrines)
● Elevated chromogranin A serum levels

Prognostic factors
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Poor prognostic features:
● Invasion into contiguous soft tissue
● Also combination of confluent tumor necrosis, coarse tumor nodularity and lack of globular cytoplasmic inclusions

Case reports
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● 43 year old man with cystic changes (Ann Diagn Pathol 2010;14:341)
● 49 year old woman with non-functional paraganglioma (Interact Cardiovasc Thorac Surg 2009;9:540)
● 50 year old man with paraganglioma that was embolized preoperatively, and was resected without the need for cardiopulmonary bypass (World J Surg Oncol 2012;10:134)
● 54 year old woman with incidental finding (J Cardiothorac Surg 2010;5:19)

Gross description
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● Firm, red-pink-brown
● Hemorrhage and necrosis common
● Partial or no capsule

Gross images
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Various tumors

Micro description
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● Tumor cells grow in tight nests of similar size (Zellballen), surrounded by fibrovascular stroma
● Cytoplasm is granular, eosinophilic or amphophilic; hyaline globules may be present
● Nuclei are round, fusiform or pleomorphic
● Chromatin may be dense or vesicular
● Usually no / scant mitotic figures
● Occasionally contain melanin

Micro images
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Various images

Positive stains
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● Neurofilament, reticulin (highlights stromal tissue), S100 (sustentacular cells), vimentin

Negative stains
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● EMA, keratin

Electron microscopy description
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● Pleomorphic secretory granules if secrete norepinephrine
● Nondescript endocrine granules in nonsecretors
● No intermediate filament whorls, no tonofibrils, no microvilli

Molecular description
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● Ret proto-oncogene mutations in exons 10, 11, 13, 15, 16 in 15%

End of Mediastinum > Other benign / low grade tumors > Paraganglioma

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