Anaplastic thyroid carcinoma mimicking a malignant pleural mesothelioma: Clues for diagnosis

Our plain-English summary of Anaplastic thyroid carcinoma mimicking a malignant pleural mesothelioma: Clues for diagnosis, by T. Capron, S. Giusiano, V. Bourinet, et al (Thoracic Cancer, 2019).

The study

• Authors: T. Capron, S. Giusiano, V. Bourinet, S. Laroumagne, H. Dutau, P. Astoul
• Journal: Thoracic Cancer
• Published: 2019;10(11):2175-2178
• Type of article: Case report
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Pleural metastasis of thyroid carcinoma is very rarely encountered in the evaluation of pleural effusion and diagnosis may be challenging. However, an anaplastic transformation of papillary thyroid carcinoma (PTC), although a rare condition, should be considered even after a prolonged period of patient follow-up. Here we report a case of anaplastic thyroid carcinoma mimicking malignant pleural mesothelioma diagnosed nine years after the initial diagnosis of PTC and detail the clues used to orient and confirm the diagnosis.

© 2019 The Authors. Thoracic Cancer published by China Lung Oncology Group and John Wiley & Sons Australia, Ltd.

In plain English

This case report described one 77-year-old man in Marseille, France. He had worked as a warehouseman, including a few years in shipyards where he was exposed to asbestos. Nine years earlier he had been treated for papillary thyroid carcinoma (PTC). He developed a large fluid build-up around the left lung. A PET/CT scan showed strong uptake in the left pleura, and doctors strongly suspected malignant pleural mesothelioma. His breathing was too poor for a pleuroscopy, so pleural biopsies were taken through the skin. Fluid cytology found mostly lymphocytes (82%) and no malignant cells. Thyroglobulin, a thyroid marker, was low in both blood and pleural fluid. The biopsies showed a malignant, poorly differentiated growth of spindle-shaped cells. These cells stained strongly for PAX-8, while the mesothelial markers calretinin, cytokeratin 5/6 and WT-1 were negative. A BRAF mutation was also found. The diagnosis was anaplastic thyroid carcinoma at the pleural site, not mesothelioma. The authors concluded that this disease could be considered in patients with a past history of PTC, even after long-term follow-up.

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)
• Who was studied: one 77-year-old male patient who had never smoked, treated at North University Hospital, Marseille, France; past history of papillary thyroid carcinoma (PTC) treated by total thyroidectomy nine years earlier
• Exposure: asbestos exposure during a few years of work in shipyards (fiber type not stated)
• Main results:
  • PET/CT showed strong FDG uptake in the left pleura (SUVmax 12 g/mL), and doctors strongly suspected malignant mesothelioma
  • Pleural fluid cytology showed predominantly lymphocytes (82%) and no malignant cells
  • Blood thyroglobulin was 2.8 ng/mL, its lowest level in five years, and pleural fluid thyroglobulin was 1.1 ng/mL, at the lower detection limit
  • Pleural biopsies showed a malignant poorly differentiated proliferation of fusiform (spindle-shaped) cells
  • Tumor cells stained strongly positive for PAX-8 (and were negative for TTF1 and thyroglobulin)
  • Mesothelial markers calretinin, cytokeratin 5/6 and WT-1 were negative
  • A BRAF mutation was found in the patient
  • The diagnosis was anaplastic thyroid carcinoma at the pleural site
• The authors' conclusion: The authors concluded that this disease could be considered in patients with a past history of PTC, even after long-term follow-up

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: Carcinoma, Pleural Mesothelioma, Metastasis, Pleural Effusion.

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