Malignant Mesothelioma

Malignant Mesothelioma

Cyril Fisher, MD, DSc, FRCPath

Low magnification of a section of the lung shows pleural thickening image by malignant mesothelioma. The tumor also extends along fissures and septa.

Hematoxylin & eosin shows microglandular, tubular, and papillary patterns of malignant mesothelioma with papillae growing within cystic spaces.



  • Malignant mesothelioma (MM)


  • Diffuse mesothelioma


  • Malignant tumor of mesothelial cells arising in pleura, peritoneum, or pericardium


Environmental Exposure

  • Asbestos

    • Occupational exposure

      • Mining, construction, vehicle maintenance, shipbuilding

      • Risk relates to intensity and duration of exposure

    • Amphibole fiber types most carcinogenic

      • Persist in lung with or without tissue reaction

      • Crocidolite and amosite have highest risk

      • Longer, thinner fibers more oncogenic

    • Latent period: 15-40 years

  • Occasionally other fiber types implicated, e.g., erionite

Infectious Agents

  • SV40 DNA oncogenic virus

    • Viral sequences found in some mesotheliomas

    • Contaminated polio vaccine unproven association


  • Therapeutic

  • Contrast media, e.g., thorium dioxide

Chronic Inflammation

  • Rarely after prolonged fibrosing inflammation, e.g., empyema



  • Incidence

    • Geographic variation

      • In USA, ˜ 20 cases per million of population in males, now peaked and declining

      • In UK, Australia, incidence higher and increasing

      • In Europe, incidence beginning to plateau

  • Age

    • Most > 60 years

    • Occasional cases at any age

  • Gender

    • 5-10x more common in males

    • Only 20% of cases in females are asbestos-related


  • Dyspnea, chest pain, cough, weight loss

  • Abdominal pain, distension, vague mass

Natural History

  • Multiple small lesions fuse to form diffuse sheet

  • Invades underlying organs and adjacent structures

    • Lung, mediastinum, through diaphragm, chest wall

    • Viscera, abdominal wall

  • Metastasizes

    • To lung, lymph nodes

    • Rarely to liver, bone, brain, kidney, adrenal


  • Options, risks, complications

    • Multimodal therapy more effective than single

  • Surgical approaches

    • Extrapleural pneumonectomy

    • Decortication

  • Adjuvant therapy

    • Chemotherapy and radiotherapy can prolong survival

    • More often palliative


  • Poor

    • Median survival: 7 months; mortality: 100%

  • Desmoplastic sarcomatoid variant is most aggressive


General Features

  • Pleural effusion

  • Diffuse pleural thickening extending into fissures

  • Peritoneal thickening

  • Mass


General Features

  • Multiple small nodules grow and coalesce

  • Firm diffuse white tumor o Encases lung

    • Locules contain fluid

    • Invades adjacent structures

      • Lung, mediastinum, diaphragm

      • Chest wall, abdominal wall


Histologic Features

  • Epithelioid malignant mesothelioma

    • Polygonal, cuboidal, or flattened discohesive cells

    • Cytoplasm eosinophilic, rarely clear

    • Mild nuclear pleomorphism, variable mitoses

    • Sheet-like, tubular, papillary, microglandular, or mixed patterns

    • Psammoma bodies

    • Variable stromal collagen, inflammation, rare myxoid change

    • Asbestos bodies in adjacent tissues

  • Sarcomatoid malignant mesothelioma

    • Fibrosarcoma-like fascicles

    • Variably pleomorphic spindle cells

    • Giant cells

    • Fibrosis, hyalinization (desmoplastic variant)

    • Necrosis

    • Heterologous osteosarcoma, chondrosarcoma, rhabdomyosarcoma

  • Biphasic malignant mesothelioma

    • Mixed epithelioid and sarcomatoid morphology

  • Other histological variants of malignant mesothelioma

    • Small cell

    • Clear cell

    • Deciduoid

    • Lymphohistiocytoid

    • Pleomorphic

Predominant Pattern/Injury Type

  • Diffuse

Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Malignant Mesothelioma
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