A case of cytokeratin-negative sarcomatoid malignant pleural mesothelioma

Our plain-English summary of A case of cytokeratin-negative sarcomatoid malignant pleural mesothelioma, by K. Inafuku, Y. Tsuura, T. Morohoshi, et al (Pathology International, 2018).

The study

• Authors: K. Inafuku, Y. Tsuura, T. Morohoshi, K. Ando, H. Masuda, K. Nabeshima, M. Masuda
• Journal: Pathology International
• Published: 2018;68(6):391-393
• Type of article: Case report, Letter
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

In plain English

This letter to the editor was a case report about one patient whose sarcomatoid malignant pleural mesothelioma was hard to diagnose. He was an 87-year-old man who had smoked a pack of cigarettes a day for forty years and had been exposed to asbestos while working in production of thermal insulating materials. He had a massive left pleural effusion. Scans showed a left pleural plaque, slight pleural thickening and a pleural nodule, but fluid cytology and two biopsies found nothing malignant. After eleven months a new mass appeared under the skin where a chest drain had been inserted. After one year and two months the pleural disease had progressed, mesothelioma was suspected, and this mass was biopsied. The tumour cells were negative for cytokeratin and for the other markers usually positive in mesothelioma. They showed loss of BAP1. Solitary fibrous tumour was ruled out. A sarcoma arising in the chest wall could not be completely excluded. The authors concluded that treating the tumour as sarcomatoid mesothelioma was most appropriate. The patient received palliative care and died after one year and six months due to the disease.

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 of a single patient, published as a letter to the editor
• Who was studied: One 87-year-old man referred to the authors' hospital in Japan with progressive shortness of breath. He had several other conditions, including variant angina, diabetes and hypertension, and had smoked a pack of cigarettes a day for forty years.
• Exposure: Asbestos exposure while working in production of thermal insulating materials. The fiber type was not stated.
• Main results:
  • Hyaluronic acid in the patient's pleural fluid was elevated to 603,000 ng/mL. Lung cancer tumour markers were within normal ranges.
  • A thoracoscopic biopsy of the pleural nodule and a CT-guided biopsy both showed no malignant findings.
  • After eleven months, CT showed a new tumour mass under the skin at the site where the chest drain had been inserted.
  • After one year and two months, CT showed that the left pleural nodule had enlarged and the pleural thickening had progressed. Mesothelioma was suspected based on the clinical course, and the mass under the skin was biopsied.
  • The biopsied tumour cells were negative for cytokeratin and for the other markers usually positive in mesothelioma. They were positive for vimentin.
  • Testing for p16 deletion by fluorescence in situ hybridization found heterozygous deletion at a rate of 79%.
  • The tumour was negative for MUC4, partially positive for GATA3, and showed loss of BAP1 on immunostaining.
  • No NAB2-STAT6 fusion gene was found and STAT6 staining was negative, so solitary fibrous tumour was ruled out.
  • Chemotherapy was not given because of the patient's age and poor general condition. The patient received palliative care and died after one year and six months due to the primary disease.
• The authors' conclusion: The authors concluded that managing the tumour as sarcomatoid malignant pleural mesothelioma was most appropriate, even though cytokeratin was negative, and that the final diagnosis rested on the clinical course and imaging findings. In their view, immunohistochemistry has a limited diagnostic role in such poorly differentiated tumours.
• Limitations the authors state:
  • The authors stated that a pleomorphic sarcoma arising in the chest wall could not be completely ruled out.

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: Sarcomatoid, Pleural Mesothelioma.

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• E-cadherin and cytokeratin subtype profiling in effusion cytology — J. Han, M.K. Kim, et al. (2004)
• Wilms tumor 1/cytokeratin dual-color immunostaining reveals distinctive staining patterns in metastatic melanoma, metastatic carcinoma, and mesothelial cells in pleural fluids: an effective first-line test for the workup of malignant effusions — J.R. Conner, E.S. Cibas, et al. (2014)
• Diagnosing tumours on routine surgical sections by immunohistochemistry: use of cytokeratin, common leucocyte, and other markers — R.N. Poston, Y.S. Sidhu (1986)
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