Localized malignant pleural sarcomatoid mesothelioma misdiagnosed as benign localized fibrous tumor

Our plain-English summary of Localized malignant pleural sarcomatoid mesothelioma misdiagnosed as benign localized fibrous tumor, by K.C. Kim, H.P. Vo (Journal of Thoracic Disease, 2016).

The study

• Authors: K.C. Kim, H.P. Vo
• Journal: Journal of Thoracic Disease
• Published: 2016;8(6):E379-84
• Type of article: Case report
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Localized malignant pleural mesothelioma (LMPM) is a rare tumor with good prognosis by surgical resection. We report an atypical case of malignant pleural sarcomatoid mesothelioma (SM) in an asymptomatic 65-year-old woman, who had no history of exposure to asbestos. She presented with a small pleural mass without pleural effusion and was misdiagnosed as a benign localized fibrous tumor (BLFT) on pathologic examination through a surgical tumor specimen. However, seven months later, the patient returned with serious cancerous symptoms. A large recurrent tumor mass was found within the chest wall invading at the old surgical resection site. SM, a subtype of LMPM, was confirmed with histopathogy and immunohistochemisty. In conclusion, malignant pleural mesothelioma (MPM) can present with typical radiologic finding similar to a BLFT, and has a wide histopathologic presentation in biopsy specimen. A thorough pathologic investigation should be attempted even when a pleural mass resembles benign, localized, and small on radiologic studies.

In plain English

This article is a case report about one patient. A 65-year-old woman with no symptoms and no reported history of asbestos exposure had a 3.5 cm mass against the pleura (the chest lining) on the left side, with no fluid around the lung. A needle biopsy found no cancer. After the mass was surgically removed, it was diagnosed as a benign localized fibrous tumor. Seven months later she came back to the authors' hospital with worsening shortness of breath and chest pain. Scans showed a large mass at the site of the earlier surgery, invading nearby ribs and the chest wall, with a large pleural effusion. A second biopsy, which tested positive for the marker D2-40, confirmed sarcomatoid malignant pleural mesothelioma. She had further surgery, including removal of the left lower lung lobe, plus chemotherapy and radiation, and was discharged home. The authors concluded that this cancer can look like a benign tumor on scans and under the microscope. They said careful pathologic testing is needed even when a mass is small and localized and the patient has no symptoms.

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 (one patient)
• Who was studied: One 65-year-old woman with no symptoms at first, seen at the authors' hospital (the corresponding author is at Ewha Womans University, Seoul, Korea). Dates of care are not given.
• Exposure: The patient had no reported history of asbestos exposure. No fiber type or other exposure is described.
• Main results:
  • At first presentation, CT showed a single, smooth, oval mass 3.5 cm in diameter against the pleura, with no pleural effusion.
  • The first needle biopsy showed no malignancy. The surgically removed mass showed benign fibroblast growth, and the tumor cells were negative for calretinin, CD34, actin and CK20. The mass was diagnosed as a benign localized fibrous tumor of the pleura.
  • Seven months after surgery, the patient had progressive shortness of breath and chest pain. CT showed a large mass in the left lower chest invading the adjacent ribs and chest wall, with a large pleural effusion.
  • A second biopsy showed spindle cells with frequent cell division, and the tumor cells were positive for D2-40. This confirmed sarcomatoid mesothelioma, a subtype of malignant pleural mesothelioma.
  • The patient had pleurectomy and left lower lobectomy, with partial removal of the affected ribs and diaphragm, plus chemotherapy and radiation therapy. She was discharged home. No length of follow-up is given.
• The authors' conclusion: The authors concluded that localized malignant pleural sarcomatoid mesothelioma may mimic benign fibrous tumors of the pleura on imaging and pathology. They concluded that careful pathological examination should be done even when a mass is small and localized and the patient has no symptoms.

Topics

Medical terms in this study, explained in our Lexicon: Sarcomatoid, Mesothelioma, Solitary Fibrous Tumor, Pleural Mesothelioma, Prognosis, Surgical Resection, Pleural Effusion, Biopsy.

Related studies

• Benign localized fibrous tumor of the pleura: report of 25 new cases — S. Enon, D. Kilic, et al. (2012)
• A case of giant benign localized fibrous tumor of the pleura — M. Biçer, S. Yaldiz, et al. (1998)
• Translocation (2;3)(p21;p26) as the sole anomaly in a benign localized fibrous mesothelioma — F. Mertens, R. Willén, et al. (1996)
• Sarcomatoid malignant peritoneal mesothelioma presenting as a localized mesenteric tumor with no previous asbestos exposure — Y.A. Notue, U.I. Mbessoh, et al. (2020)
• Localized fibrous tumor of the serosal cavities. Immunohistochemical, electron-microscopic, and flow-cytometric DNA study — A.K. el-Naggar, J.Y. Ro, et al. (1989)
• Intrapulmonary localized fibrous tumor. Intraparenchymal so-called localized fibrous mesothelioma — S.A. Yousem, S.D. Flynn (1988)

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