Pulmonary and pleural thymoma. Diagnostic application of lymphocyte markers to the thymoma of unusual site

Our plain-English summary of Pulmonary and pleural thymoma. Diagnostic application of lymphocyte markers to the thymoma of unusual site, by M. Fukayama, Y. Maeda, N. Funata, et al (American Journal of Clinical Pathology, 1988).

The study

• Authors: M. Fukayama, Y. Maeda, N. Funata, M. Koike, K. Saito, T. Sakai, T. Ikeda
• Journal: American Journal of Clinical Pathology
• Published: 1988;89(5):617-21
• Type of article: Case report
• Cited by: 36 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Two cases of the thymoma of the unusual sites were examined immunohistochemically. The one was intrapulmonary, and the other was diffuse pleural tumors. The infiltrating lymphocytes were T-cells showing OKT 6 positivity and nuclear immunoreactivity for terminal deoxynucleotidyl transferase (TdT) in the intrapulmonary tumor, like lymphocytes in the mediastinal thymoma of predominantly lymphocytic or mixed types. Although lymphocytes were dispersed in the pleural tumor, there were some TdT(+) OKT 6(-) lymphocytes and the similar finding was observed in the thymoma of predominantly epithelial type. In lung carcinomas and pleural mesotheliomas, there were no TdT(+) OKT 6(+/-) lymphocytes. Immunohistochemical studies using lymphocyte markers may be an useful tool for the diagnosis of the thymoma of ectopic site or unusual presentation.

In plain English

This article reported two patients at a Tokyo hospital with thymoma, a tumor that usually arises in the front of the chest, found in unusual places. Case 1 was a 74-year-old man with a tumor inside the right lung. Case 2 was a 55-year-old woman, a cleaning woman with no history of asbestos exposure. Her tumors spread over the lining of the right lung (the pleura) and at first suggested pleural mesothelioma or a lung cancer mimicking it. The authors stained the lymphocytes (immune cells) in these tumors with markers. They compared them with six mediastinal thymomas, four lung carcinomas and three pleural mesotheliomas. In case 1, most lymphocytes were T-cells positive for both OKT 6 and TdT, as in lymphocyte-rich and mixed thymomas. In case 2, some lymphocytes were TdT-positive but OKT 6-negative, as in epithelial-type thymomas. No lymphocytes in the lung carcinomas or mesotheliomas stained for OKT 6 or TdT. The authors concluded that lymphocyte markers may help diagnose thymoma in unusual sites. They said more experience with epithelial thymomas would be desirable to confirm their results.

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: Report of two cases, with immunohistochemical staining of tumor lymphocytes compared against control tumor tissues
• Who was studied: Two patients at Tokyo Metropolitan Komagome Hospital, Japan. Case 1 was a 74-year-old man with an intrapulmonary tumor in the right lung. Case 2 was a 55-year-old woman with diffuse right pleural tumors. Control tissues were six anterior mediastinal thymomas (two each of predominantly lymphocytic, mixed and predominantly epithelial types), three pleural mesotheliomas, and four lung carcinomas (two squamous cell, one adenocarcinoma, one large cell).
• Exposure: Not a study of asbestos exposure. The only mention is that case 2, a cleaning woman, had no history of asbestos exposure.
• Main results:
  • Case 1 (intrapulmonary tumor): the infiltrating lymphocytes were T-cells (positive with Leu 2a or Leu 3a+3b, negative with B1). Most were positive with OKT 6 and had nuclei immunoreactive for TdT.
  • Case 2 (pleural tumor): there was some accumulation of TdT-positive lymphocytes in perivascular space. The corresponding portions of serial sections had no cells positive with Leu 2a, Leu 3a+3b or OKT 6. There were no B1-positive lymphocytes.
  • Control mediastinal thymomas of predominantly lymphocytic and mixed types: the infiltrating lymphocytes were T-cells, and most had the OKT 6 epitope and TdT nuclear staining.
  • Control predominantly epithelial thymomas: lymphocytes showed no definite OKT 6 reaction, but several or many lymphocytes showed nuclear staining for TdT.
  • Control lung carcinomas: infiltrating lymphocytes were negative with OKT 6 and with anti-TdT antibody. The scattered OKT 6-positive cells were dendritic cells.
  • Control pleural mesotheliomas: lymphocytes showed no positive staining with OKT 6 or anti-TdT antibody.
  • Case 1 was free of tumor 18 months after the operation. Case 2 was free of tumor 16 months after resection.
• The authors' conclusion: The authors concluded that immunohistochemical findings in infiltrating lymphocytes may be a useful aid for diagnosing thymoma at unusual sites. They considered that the findings confirmed case 1 as an ectopic thymoma of the lung.
• Limitations the authors state:
  • The authors stated that more experience with epithelial thymomas would be desirable to confirm their results.
  • The authors could not identify ectopic thymic tissue in the resected lung of case 1, so the origin of the intrapulmonary tumor remained uncertain.

Topics

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

Medical terms in this study, explained in our Lexicon: Carcinoma, Pleural Mesothelioma.

Related studies

• Pleural metastasis of malignant thymoma. A pitfall in the CT-diagnosis of pleural mesothelioma — J. Görich, S.A. Beyer-Enke, et al. (1989)
• Cytoreductive surgery and intraoperative hyperthermic intrathoracic chemotherapy in patients with malignant pleural mesothelioma or pleural metastases of thymoma — E. de Bree, S. van Ruth, et al. (2002)
• A case of cardiac herniation after extrapleural pneumonectomy for malignant thymoma — S. Sonoda, Y. Kumagawa, et al. (2010)
• Extended pleurectomy decortication for thymoma with pleural dissemination — N. Imanishi, Y. Nabe, et al. (2019)
• Pharmacokinetics of doxorubicin and cisplatin used in intraoperative hyperthermic intrathoracic chemotherapy after cytoreductive surgery for malignant pleural mesothelioma and pleural thymoma — S. van Ruth, O. van Tellingen, et al. (2003)
• A protective role for T lymphocytes in asbestos-induced pulmonary inflammation and collagen deposition — E. Corsini, M.I. Luster, et al. (1994)

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