Intrapulmonary localized fibrous tumor. Intraparenchymal so-called localized fibrous mesothelioma

Our plain-English summary of Intrapulmonary localized fibrous tumor. Intraparenchymal so-called localized fibrous mesothelioma, by S.A. Yousem, S.D. Flynn (American Journal of Clinical Pathology, 1988).

The study

• Authors: S.A. Yousem, S.D. Flynn
• Journal: American Journal of Clinical Pathology
• Published: 1988;89(3):365-9
• Type of article: Case report
• Cited by: 122 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

This report describes three cases of intrapulmonary fibromas which are histologically identical to localized fibrous tumors of pleura (localized fibrous mesothelioma). Morphologically these tumors are characterized by a haphazard proliferation of cytologically bland spindle cells separated by variable amounts of wavy hyalinized collagen. Entrapped bronchiolar and alveolar epithelium is common. These spindle cells lack expression of cytoplasmic keratin, S-100 protein, desmin, and epithelial membrane antigen, but are strongly decorated for intracellular vimentin. The clinical behavior, differential diagnosis, and histogenesis of these lesions are discussed.

In plain English

This was a report of three patients whose lung tumors looked the same under the microscope as localized fibrous tumors of the pleura (sometimes called localized fibrous mesothelioma), but which grew inside the lung tissue. The patients were a 71-year-old man, a 55-year-old woman and an 82-year-old woman, and each tumor was removed by surgery. All three tumors were made of bland spindle cells separated by wavy collagen. None showed cell atypia, necrosis, or invasion of blood or lymph vessels. Stains done in two cases showed the tumor cells stained for vimentin but not for keratin. All three patients were free of disease at follow-up of three, fourteen and eight months. The authors concluded that these tumors were the lung equivalent of the pleural tumors and called them fibromas of lung. The article did not report whether the patients had been exposed to asbestos. Its introduction, citing earlier work, stated that these localized tumors, unlike diffuse mesothelioma, have no association with asbestos. The text is inconsistent about which tumors touched the pleura.

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 series (report of three cases), with pathology and immunostaining of the removed tumors
• Who was studied: Three patients with intrapulmonary tumors, seen at the pathology departments of Presbyterian-University Hospital of Pittsburgh and Yale University School of Medicine: a 71-year-old white man, a 55-year-old Hispanic woman and an 82-year-old white woman. Dates of the cases were not given.
• Exposure: No exposure was studied, and the article did not report the asbestos exposure history of any patient. The introduction states, as background from earlier literature, that localized fibrous tumors, unlike diffuse mesothelioma, have no association with asbestos exposure. Smoking was mentioned: case 1 had a long history of cigarette smoking, and no smoking history was offered for case 2.
• Main results:
  • Case 1 (71-year-old man): a 3.5-cm nodule was removed from the right middle lobe. It was separated from the visceral pleura by 2 mm. The patient was free of disease three months after surgery.
  • Case 2 (55-year-old woman): a 1.5-cm mass was removed from the lingula of the left upper lobe. She was free of recurrent lung disease fourteen months after surgery.
  • Case 3 (82-year-old woman): a 3.0-cm mass was removed from the right lower lobe. It had been suspected to be lung carcinoma, but the biopsied mediastinal nodes were unremarkable. She was alive and well without recurrence at eight months.
  • In all three tumors, cytologic atypia was absent and mitoses were very few. Necrosis was absent, and vascular and lymphatic invasion were not identified.
  • In cases 2 and 3, the tumor spindle cells did not stain for keratin but did stain for vimentin. Only the trapped lung epithelium stained for keratin. Stains for S-100 protein, desmin and epithelial membrane antigen did not stain the tumor cells.
  • The authors interpreted vimentin staining without keratin staining as strong support for a mesenchymal (connective-tissue) origin of these tumors.
• The authors' conclusion: The authors concluded that these lung tumors represent the lung equivalent of localized fibrous tumors of the pleura. Where no connection to the pleura is seen, they designate them fibromas of lung. They recommended complete surgical excision because the tumors' behavior is hard to predict.
• Limitations the authors state:
  • The authors stated it is unclear whether criteria used to predict aggressive behavior in pleural fibrous tumors can be applied to these lung tumors.

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: Solitary Fibrous Tumor, Mesothelioma, Pleura, Spindle Cell, Collagen, Epithelium, S-100, Desmin.

Related studies

• 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)
• Localized fibrous tumors (LFTs) of the pleura: clinical data, asbestos burden, and syntactic structure analysis applied to newly defined angiogenic/growth-regulatory effectors — K. Kayser, J. Trott, et al. (2005)
• Solitary (localized) fibrous mesothelioma: evidence against mesothelial cell origin — P.A. Dervan, B. Tobin, et al. (1986)
• Intrapulmonary location of benign solitary fibrous tumor — Z.M. Alghamdi, S.A. Othman, et al. (2020)
• Fine-needle aspiration cytology of localized fibrous tumor of pleura — D. Dusenbery, M.M. Grimes, et al. (1992)
• Benign localized fibrous tumor of the pleura: report of 25 new cases — S. Enon, D. Kilic, et al. (2012)

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