Lung tumor
Benign tumors
Solitary fibrous tumor

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

Revised: 20 January 2016, last major update January 2016

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Solitary fibrous tumor [title] lung
Definition / General
Essential Features
  • Intrapulmonary solitary fibrous tumors are rare but appear to show similar characteristics to pleural based tumors
  • Majority show NAB2-STAT6 gene fusion with nuclear STAT6 reactivity on immunohistochemistry
  • Even bland tumors may have aggressive behavior, although most are indolent
Epidemiology
  • Predominantly middle-aged to older adults (ages 40 to 80s), no sex predilection
Sites
  • Arises most commonly from pleura, with uncommon inward growth into lung parenchyma
  • Extremely rare to arise entirely within lung parenchyma
  • Generally peripheral in location
Pathophysiology
  • Growth in size over time may raise concern
  • 10 - 15% behave in malignant fashion
Etiology
  • Arise from fibroblastic elements of the submesothelial zone
  • May develop from visceral pleura or interlobular septa but grow towards / into the lung parenchyma
Clinical Features
  • Often discovered incidentally on chest imaging but may show non-specific symptoms (cough, sputum, dyspnea, chest pain)
  • Larger tumors (>7 cm) are associated with hypoglycemia, pleural effusion, pulmonary osteoarthropathy
Diagnosis
  • Difficult to establish diagnosis based on imaging, bronchoscopic examination and limited biopsy specimens
  • Immunohistochemistry is helpful to support diagnosis and rule out other entities
Radiology Description
  • Generally non-specific appearance
  • Xray: abnormal shadow / nodule, discrete homogenously dense mass, lobulated
  • CT: Well circumscribed nodule, enhances with IV contrast, may show necrotic foci
  • PET: no / minimal uptake in most cases
  • MRI: may show variable density and intralesional hemorrhage
Radiology Images

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CT scan

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Solitary mass

Prognostic Factors
Case Reports
Treatment
  • Surgical resection based on size and location
Gross Description
  • Firm, rounded to ovoid, lobulated, well circumscribed, solid
  • Tumor size variable, from 2 to 20+ cm
  • Vaguely "whorled", gray-white cut surface
  • Variable cysts, hemorrhage, necrosis
Gross Images

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Multinodular

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Excised tumor, pleura

Micro Description
  • Markedly collagenous stroma ("ropey collagen") with irregularly distributed thick walled "staghorn" vessels and bland spindle cells
  • Variable cellularity and histologic appearance, including "patternless pattern"
  • Patterns: adenofibromatous (Int J Surg Pathol 2005;13:79), fibrosarcomatous, hemangiopericytic, neural-like plexiform
  • Adenofibromatous appearance from entrapped normal airspaces at edge
  • May have myxoid stroma
  • Areas may resemble pleomorphic high grade sarcoma (pleomorphism, tumor giant cells, mitotic figures) intermixed with areas of conventional SFT
Micro Images

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CD34

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Benign and malignant tumors

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Various stains, pleura

Cytology Description
Cytology Images

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Pleura

Positive Stains
Electron Microscopy Description
  • Fibroblast-like with only basic intracellular organelles
Molecular / Cytogenetics Description