Salivary gland type tumors

Pleomorphic adenoma

Last author update: 1 May 2016
Last staff update: 24 April 2023 (update in progress)

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PubMed Search: Pleomorphic adenoma lung [title]

Roseann I. Wu, M.D., M.P.H.
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Cite this page: Wu R. Pleomorphic adenoma. website. Accessed June 2nd, 2023.
Definition / general
  • Pulmonary adenoma includes bronchial adenoma, alveolar adenoma, papillary adenoma
  • Pleomorphic adenoma could be considered a type of bronchial adenoma
  • Benign tumor with biphasic growth, resembling counterpart in salivary glands; need to exclude metastasis from salivary glands

  • Related entities:
    • Alveolar adenoma:
      • Benign tumor in asymptomatic patients
      • Presents as coin lesion, usually in peripheral lung, consisting of small cystic spaces lined by type II pneumocytes and containing fluid
      • Interstitial cellular component consists of epithelioid and spindle shaped cells
    • Bronchial gland adenoma:
      • Includes oncocytoma and mucus gland adenoma, a rare, solitary, benign, well circumscribed, multicystic, predominately exophytic bronchial tumor
    • Carcinoma ex pleomorphic adenoma:
    • Intracapsular carcinoma ex pleomorphic adenoma:
      • Malignant component does not breach the capsule of the parent tumor, no metastatic potential
    • Papillary adenoma:
      • Arises in peripheral lung, composed of type II pneumocytes (club cells), TTF1+
      • Rarely has infiltrative features (Virchows Arch 2000;436:289)
Essential features
  • Primary pulmonary pleomorphic adenoma is a very rare benign tumor that tends to arise in the large airways
  • Tumors tend to show small, branching, double layered ductules rather than ducts and less cartilaginous stroma as compared to pleomorphic adenomas arising in the salivary gland
  • Keratin and vimentin staining of the epithelial component supports diagnosis of primary pulmonary tumor as opposed to only keratin staining in salivary gland tumors (Arch Pathol Lab Med 2003;127:621)
  • Prognosis is generally good, but cases of carcinoma ex pleomorphic adenom have been reported
  • Pleomorphic adenoma is also known as mixed tumor
  • Overlaps with “myoepithelioma”, which could be used for lesions with less cartilaginous and ductal differentiation
  • Very rare (< 40 cases reported), predominantly in young adults, age range 8 - 74 years
  • Possibly shows slight F > M
  • Usually in trachea and major bronchi, rarely in distal bronchi
  • Controversial, possibly from tracheal and bronchial submucosal glands or primitive stem cells
Clinical features
  • Frequently asymptomatic but can present with dyspnea, hemoptysis, fever, weight loss or effusion
  • Depending on location, may cause obstruction of airway
  • Broader differential diagnosis on biopsy specimens but generally straightforward on resection specimen
Radiology images

Images hosted on other servers:
Enhanced and nonenhanced CT scan

Enhanced and nonenhanced CT scan

Prognostic factors
  • Generally indolent; no features to predict rare cases of metastasis
Case reports
  • Complete conservative surgical excision, but may recur many years later
  • Endobronchial resection may be an option in some cases (Intern Med 2008;47:1117)
Gross description
  • Bronchial lesions are typically polypoid
  • Peripheral lesions are usually attached to bronchi, well circumscribed, no capsule, 1 - 16 cm, gray - white, soft, rubbery with chondroid cut surface, may have tumor tongues outside circumscribed margin
Gross images

Images hosted on other servers:
Cut surface shows a well defined<br>mass, whitish to yellowish,<br>partly myxoid, solid and cystic

Cut surface shows a well defined
mass, whitish to yellowish,
partly myxoid, solid and cystic

Microscopic (histologic) description
  • Generally less cartilaginous stroma than salivary gland counterpart, with small branching ductules rather than ducts
  • Nests, tubules, trabeculae
  • Mixture of round or oval epithelial cells and myoepithelial cells in chondromyxoid or fibromyxoid stroma with focal hyalinization
  • Generally nuclear atypia / necrosis / hemorrhage / mitoses, occasional multinucleated giant cells
  • May show myoepitheliomatous, plasmacytoid, squamous features
  • Lumina may contain PAS+ eosinophilic secretions
Microscopic (histologic) images

Contributed by Roseann Wu, M.D., M.P.H.
Various images Various images Various images Various images Various images

Various images

Images hosted on other servers:
Metastasizing tumor with benign features

Metastasizing tumor with benign features

Cytology description
  • Fibrillary stroma mixed with bland basaloid epithelial cells
Positive stains
Negative stains
Differential diagnosis
Additional references
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