Malignant mesothelioma with squamous differentiation

Our plain-English summary of Malignant mesothelioma with squamous differentiation, by H. Tanaka, Y. Akiyama, A. Kitamura, et al (Histopathology, 2018).

The study

• Authors: H. Tanaka, Y. Akiyama, A. Kitamura, N. Matsumoto, M. Tomita, H. Kataoka
• Journal: Histopathology
• Published: 2018;72(7):1216-1220
• Type of article: Case report
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Aims: We report the autopsy findings of a 58-year-old man with malignant mesothelioma in the left pleural cavity.

Methods And Results: The patient had a history of asbestos exposure, and the chest computed tomography scan on initial admission demonstrated an extrapleural sign, suggesting a nodular lesion in the chest wall. However, no nodular lesions were detectable in either of his lungs. In spite of chemotherapy, he died 4 months after the initial admission. An autopsy revealed markedly thickened pleura in a large section of the left pleural cavity without visible intrapulmonary primary tumour lesions. Histological examination of a biopsy specimen obtained prior to chemotherapy and that of an autopsy specimen showed that the pleural tumour was composed of a mixture of mesothelioma and tumour cells with squamous differentiation mimicking squamous cell carcinoma.

Conclusions: To the best of our knowledge, this is the first case report of mesothelioma with extensive squamous differentiation in the English-language literature. The extensive squamous differentiation reminiscent of squamous cell carcinoma can be a pitfall in the pathological diagnosis of pleural cytology and that of biopsy specimens from patients with mesothelioma. Here, we report autopsy findings of a case of malignant mesothelioma with portions of extensive squamous differentiation, mimicking a squamous cell carcinoma.

© 2018 John Wiley & Sons Ltd.

In plain English

This case report described the autopsy of a 58-year-old Japanese man with malignant mesothelioma in the left pleural cavity. He had been exposed to asbestos while working as a builder, though details were unclear, and he had never smoked. Scans showed fluid around the left lung and a chest-wall nodule, with no tumor seen in the lungs. A biopsy first suggested squamous cell carcinoma, a different cancer, because parts of the tumor looked squamous. However, the tumor cells stained for GATA3, which the authors described as consistent with mesothelioma. Chemotherapy worked poorly, and he died about 8 months after his illness began. At autopsy the tumor had thickened the left pleura and spread through the diaphragm to the surfaces of the stomach, transverse colon and retroperitoneum. No primary squamous cell carcinoma was found elsewhere. The authors diagnosed biphasic malignant mesothelioma with extensive squamous differentiation and counted 1367.99 asbestos bodies per gram of dried left lung. They concluded it was the first such case in the English literature and showed a potential pitfall in diagnosis.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case report (single patient, including autopsy findings)
• Who was studied: one 58-year-old Japanese man with no smoking history, treated at the University of Miyazaki hospital, Japan
• Exposure: asbestos exposure while working as a builder. Details of the exposure were unclear, and no fiber type was reported.
• Main results:
  • The pleural biopsy initially suggested squamous cell carcinoma rather than malignant mesothelioma, because the tumor cells showed distinct squamous differentiation.
  • Tumor cells in the biopsy were immunoreactive for GATA3, which the authors described as consistent with mesothelioma but unlikely for squamous cell carcinoma.
  • The hyaluronic acid level in the patient's pleural effusion was high (103,000 ng/mL).
  • Chemotherapy had poor efficacy. The patient died about 8 months after the onset of illness.
  • At autopsy the tumor had invaded through the diaphragm and formed nodules on the surfaces of the stomach, transverse colon and retroperitoneum.
  • No primary squamous cell carcinoma was found in other organs examined at autopsy.
  • Electron microscopy did not show the features that strongly indicate squamous cell carcinoma (well-developed desmosomes and tonofilaments).
  • The final diagnosis was malignant mesothelioma of biphasic type with extensive squamous differentiation.
  • A dried fragment of the patient's left lung contained 1367.99 asbestos bodies per gram.
• The authors' conclusion: The authors concluded that this was the first case report in the English literature of malignant mesothelioma mimicking well-differentiated squamous cell carcinoma, and that it shows a potential pitfall in diagnosing malignant pleural mesothelioma.
• Limitations the authors state:
  • Details of the patient's asbestos exposure were unclear.
  • The authors noted that high hyaluronic acid in pleural fluid has also been reported in a small number of lung cancers.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Malignant Mesothelioma, Autopsy, Pleural Cavity, Asbestos Exposure, Chemotherapy, Pleura, Biopsy, Mesothelioma.

Related studies

• Malignant pleural neoplasm with both differentiation of epithelioid mesothelioma and squamous-cell carcinoma, a rare phenomena — A. Re, D. Shersher, et al. (2021)
• p40 is the best marker for diagnosing pulmonary squamous cell carcinoma: comparison with p63, cytokeratin 5/6, desmocollin-3, and sox2 — T. Tatsumori, K. Tsuta, et al. (2014)
• Utility and pitfalls of immunohistochemistry in the differential diagnosis between epithelioid mesothelioma and poorly differentiated lung squamous cell carcinoma — K. Kushitani, V.J. Amatya, et al. (2017)
• Cytomorphological features of metastatic squamous cell carcinoma in serous effusions — C.C. Huang, C.W. Michael (2014)
• Small orangiophilic squamous-like cells: an underrecognized and useful morphological feature for the diagnosis of malignant mesothelioma in pleural effusion cytology — L. Chen, S.G. Caldero, et al. (2014)
• Pulmonary acantholytic squamous cell carcinoma with focal signet ring cell morphology mimicking malignant mesothelioma on fine needle aspiration cytology: a case report — S.E. Choi, H.S. Park (2016)

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