Clinical and pathological characteristic of metastatic malignant mesothelioma initially diagnosed by lymph node biopsy

Our plain-English summary of Clinical and pathological characteristic of metastatic malignant mesothelioma initially diagnosed by lymph node biopsy, by X.L. Zhu, L.M. Gao, F. Li, et al (Pathology, Research and Practice, 2017).

The study

• Authors: X.L. Zhu, L.M. Gao, F. Li, W.P. Liu, W.Y. Zhang, G.D. Li, X.H. Zhang, M. Chen, X.Y. Liu, S. Zhao
• Journal: Pathology, Research and Practice
• Published: 2017;213(6):598-605
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: It is a great challenge for pathologists to initially diagnose metastatic malignant mesothelioma (MM) by the lymph node biopsy without any history of primary MM. Because the onset of MM is hidden and the metastatic MM in lymph node is relatively uncommon. Besides, morphologic and immuohistochemistry features of MM are similar to other tumors.

Methods: In order to improve the initial diagnostic accuracy of metastatic MM from LN biopsy and to reduce or avoid the possibility of missed diagnosis or misdiagnosis, we had collected the clinical and pathological data of the metastatic MM cases in our department, and summarized the characteristics of morphological, immunohistochemical and fluorescence in situ hybridization (FISH) results.

Results: Seven patients (4 males and 3 females) with 21-73 year-old had been included in our study. Six cases showed serous cavity effusion, serosal thickening and systemic multiple lymph node enlargement. The "moderate, nice" tumor cells were arranged in variable patterns. Mitosis was hardly to be found and necrosis was absent. Four immunohistochemical staining panels and FISH detection had been used for diagnosis and differential diagnosis of MM. All cases expressed broad-spectrum epithelial markers and at least 2 mesothelial-cell-origin markers. None were positive for specific-tissue-origin markers, and all cases were diagnosed of malignancy according to immunohistochemical markers and detection of pl6 gene deletion.

Conclusion: It is necessary for us to keep our awareness of metastatic MM in lymph node. Correct diagnosis of MM metastasis by lymph node biopsy were based on detailed understanding of the clinical manifestation and the image data, careful observation of morphologic characteristics, and properly using immunohistochemical markers or FISH detection if necessary for diagnosis and differential diagnosis.

Copyright © 2017 Elsevier GmbH. All rights reserved.

In plain English

This report described seven patients at West China Hospital of Sichuan University whose malignant mesothelioma was first diagnosed by lymph node biopsy, with no known primary tumor. They came from 31 metastatic tumor cases diagnosed by lymph node biopsy between January 2009 and April 2015. The patients, 4 men and 3 women, were aged 21 to 73. Two had asbestos contact; no fiber type was given. Six had body-cavity fluid, thickened cavity linings and widespread lymph node enlargement. Clinicians had misdiagnosed all seven as lymphoma, metastatic tumor or tuberculosis. All tumors stained positive for broad epithelial markers and at least two mesothelial markers, and negative for other specific-tissue markers, except partial P63 staining in one case and weak local BerEp4 staining in three. A gene test (FISH) found p16 deletion in 6 of 7 cases. None had a biopsy of the primary site. Four patients given only supportive treatment died after 4 to 6 months; median survival was 6 months. The authors concluded that correct diagnosis rests on clinical and imaging findings, careful tissue examination, and proper use of staining or FISH.

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: Retrospective single-center case series (pathology review of 7 cases), with a comparison to 27 previously published cases
• Who was studied: 7 patients (4 males, 3 females, aged 21 to 73) with metastatic malignant mesothelioma first diagnosed by lymph node biopsy. They were selected from 31 cases of metastatic tumor diagnosed by lymph node biopsy without any primary tumor history, January 2009 to April 2015, at the Department of Pathology, West China Hospital of Sichuan University, Chengdu, China
• Exposure: Asbestos exposure history was recorded for 2 of the 7 patients. No fiber type, product, job or dose was given. The study's focus was diagnostic (tissue staining and FISH), not exposure.
• Main results:
  • Six of the 7 patients showed serous cavity effusion, serosal thickening and systemic lymph node enlargement
  • Based on clinical and imaging data, clinicians misdiagnosed all 7 cases as lymphoma, metastatic tumor or tuberculosis
  • Tumor cells in all 7 cases expressed the broad-spectrum epithelial markers PCK and CK7
  • Tumor cells in all 7 cases expressed at least 2 mesothelial markers. Positive rates were CR 71%, HBME-1 71%, WT-1 71%, D2-40 57% and CK5/6 57%
  • Specific-tissue-origin markers were reported negative in all cases. The exceptions were 1 case partially positive for P63 and 3 cases locally weak-positive for BerEp4
  • Among markers used to separate benign from malignant mesothelial cells, GLUT-1 was positive in all 7 cases. Desmin was negative in 6 cases and p16 staining was negative in 5
  • FISH detected p16 deletion in 6 of 7 cases (86%): heterozygous in 5 (71%) and homozygous in 1 (14%)
  • Only 3 of the 7 patients received chemotherapy. The other 4 received mainly symptomatic supportive anti-inflammation therapy and died after 4 to 6 months. Median survival was 6 months
  • None of the 7 patients had a biopsy or cytology of the primary site. In 6 cases the primary site was found by imaging
• The authors' conclusion: The authors concluded that correct diagnosis of metastatic mesothelioma from a lymph node biopsy depended on detailed understanding of the clinical picture and imaging, careful observation of tissue features, and proper use of immunohistochemical markers or FISH when needed. They also wrote that the absence of asbestos contact cannot by itself rule out metastatic mesothelioma.
• Limitations the authors state:
  • The meaning of the two p16 deletion patterns (homozygous versus heterozygous) remained unclear
  • More cases are needed to learn whether mesothelioma with lymph node metastasis is more invasive and has a poorer prognosis
  • Metastatic tumors should normally be confirmed by biopsy of the primary site, but such cases rarely get one, and none of these 7 did

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, Biopsy, Misdiagnosis, Fluorescence In Situ Hybridization (FISH), Necrosis, Immunohistochemistry, Differential Diagnosis, Metastasis.

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• Hyperplastic mesothelial cells in lymph nodes: report of six cases of a benign process that can stimulate metastatic involvement by mesothelioma or carcinoma — P. Argani, J. Rosai (1998)
• Diagnosis of malignant pleural mesothelioma by axillary lymph node biopsy — S.B. Kim, B. Varkey, et al. (1987)
• Lymph node involvement and metastatic lymph node ratio influence the survival of malignant pleural mesothelioma: a French multicenter retrospective study — I. Hysi, F. Le Pimpec-Barthes, et al. (2014)
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