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Malignant pleural mesothelioma with heterologous elements
  1. Toshiaki Kawai1,
  2. Reishi Seki2,
  3. Kuniharu Miyajima3,
  4. Hiroshi Nakashima4,
  5. Takayuki Takeda5,
  6. Tomoyuki Murakami6,
  7. Keisuke Aoe7,
  8. Kazunori Okabe7,
  9. Keiichi Homma8,
  10. Yoshitane Tsukamoto9,
  11. Koichi Sunada10,
  12. Yasuhiro Terasaki11,
  13. Maki Iida12,
  14. Hideki Orikasa13,
  15. Kenzo Hiroshima14
  1. 1 Toda Central Medical Laboratory, Toda, Japan
  2. 2 Department of Diagnostic Pathology, Tokyo Saiseikai Central Hospital, Tokyo, Japan
  3. 3 Department of Thoracic Surgery and Oncology, Niizashiki Central General Hospital, Niiza, Japan
  4. 4 Department of Preventive Medicine and Public Health, National Defense Medical College, Tokorozawa, Japan
  5. 5 Division of Respiratory Medicine, Uji-Tokushukai Medical Center, Uji, Japan
  6. 6 Department of Pathology, Kanmon Medical Center, Shimonoseki, Japan
  7. 7 Departments of Medical Oncology, and Thoracic Surgery, Yamaguchi Ube Medical Center, Ube, Japan
  8. 8 Department of Pathology, Niigata Cancer Center Hospital, Niigata, Japan
  9. 9 Department of Pathology, Takarazuka City Hospital, Takarazuka, Japan
  10. 10 Division of Respiratory Medicine, Saiseikai Yokohamashi Tobu Hospital, Yokohama, Japan
  11. 11 Department of Analytic Human Pathology, Nippon Medical School Hospital, Tokyo, Japan
  12. 12 Department of Pathology, Yokosuka General Hospital Uwamachi, Yokosuka, Japan
  13. 13 Department of Pathology, Kawasaki Municipal Hospital, Kawasaki, Japan
  14. 14 Department of Pathology, Tokyo Women’s Medical University Yachiyo Medical Center, Yachiyo, Japan
  1. Correspondence to Dr Toshiaki Kawai, Toda Central Medical Laboratory, Toda, Saitama, Japan; t_kawai{at}


Aims Malignant pleural mesothelioma with heterologous elements (such as osseous, cartilaginous or rhabdomyoblastic differentiation) is very rare. We tried to differentiate such mesothelioma cases from extraskeletal pleural osteosarcoma, which is very challenging.

Methods We compared 10 malignant pleural mesotheliomas (three biphasic and seven sarcomatoid types) with two pleural osteosarcomas using clinicopathological and immunohistochemical methods, and also fluorescence in situ hybridisation (FISH) to examine for homozygous deletion of p16.

Results The median age was 72 years for mesotheliomas, and 69 years for osteosarcoma. For mesothelioma, eight cases were male and two were female. Growth was diffuse in all mesothelioma cases except case 10, where it was localised, as it was for the two osteosarcomas. Among mesothelioma cases, 80% displayed osteosarcomatous and 60% chondromatous elements, while 10% exhibited rhabdomyoblastic ones. Immunohistochemical labelling for calretinin and AE1/AE3 was present in 8/10 and 7/10 mesotheliomas, respectively, but in only one osteosarcoma. Loss of methylthioadenosine phosphorylase was seen in 5/7 mesotheliomas. FISH analysis revealed homozygous deletion of p16 in 5/8 mesothelioma and 2/2 osteosarcoma. Median survival was 6.5 months after biopsy or surgical operation in mesothelioma, and 12 months after operation in osteosarcoma.

Conclusions Although median survival was longer for osteosarcoma than for malignant mesothelioma, we could not differentiate mesothelioma from pleural osteosarcoma on the combined basis of clinicopathological and immunohistochemical data, and FISH analysis. However, diffuse growth was more frequent in mesothelioma than in osteosarcoma.

  • pleura
  • immunohistochemistry
  • fish

Data availability statement

Data are available on reasonable request.

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Data availability statement

Data are available on reasonable request.

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  • Handling editor Runjan Chetty.

  • Contributors They analysed their cases carefully, and contributed to our analysis.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; internally peer reviewed.