Mesenchymal tumors
Solitary fibrous tumor

Topic Completed: 1 January 2016

Minor changes: 17 March 2021

Copyright: 2003-2021,, Inc.

PubMed Search: Solitary fibrous tumor [title] lung

Roseann Wu, M.D., M.P.H.
Page views in 2020: 9,557
Page views in 2021 to date: 2,713
Cite this page: Wu R. Solitary fibrous tumor. website. Accessed May 11th, 2021.
Definition / general
  • Similar to solitary fibrous tumors arising from pleura and other sites (bladder, CNS, colon, ear, eye, kidney, liver, mediastinum, nasal, prostate, soft tissue, thyroid) but arises as intrapulmonary mass
  • May be difficult to diagnose with imaging and biopsy alone
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
  • Predominantly middle-aged to older adults (ages 40 to 80s), no sex predilection
  • Arises most commonly from pleura, with uncommon inward growth into lung parenchyma
  • Extremely rare to arise entirely within lung parenchyma
  • Generally peripheral in location
  • Growth in size over time may raise concern
  • 10 - 15% behave in malignant fashion
  • 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
  • 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

CT scan

Prognostic factors
Case reports
  • 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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Excised tumor, pleura

Excised tumor, pleura

Microscopic (histologic) 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
Microscopic (histologic) images

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Various stains, pleura Various stains, pleura

Various stains, pleura

Cytology description
Cytology images

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Positive stains
Electron microscopy description
  • Fibroblast-like with only basic intracellular organelles
Molecular / cytogenetics description
Differential diagnosis
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