Solitary fibrous tumor of the mediastinum. A report of 14 cases

Our plain-English summary of Solitary fibrous tumor of the mediastinum. A report of 14 cases, by G.B. Witkin, J. Rosai (The American Journal of Surgical Pathology, 1989).

The study

• Authors: G.B. Witkin, J. Rosai
• Journal: The American Journal of Surgical Pathology
• Published: 1989;13(7):547-57
• Cited by: 214 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Fourteen cases of a mediastinal neoplasm identical to solitary fibrous tumor (so-called fibrous mesothelioma) of the pleura were observed. The lesions presented with cough, chest pain, dyspnea, or as asymptomatic masses detected radiographically. Two patients had associated hypoglycemia. Eleven of the tumors were in the antero-superior mediastinum. One arose on a pedicle from the thymus, and another had entrapped thymic elements. Tumor cells were variably immunoreactive for vimentin and actin, but not for keratin, and lacked ultrastructural evidence of mesothelial or epithelial differentiation. Eight cases had highly cellular mitotically active regions of which six of seven with follow-up behaved aggressively; the exception was the pedunculated tumor. A 13-cm, histologically bland tumor has recurred twice. Aggressive behavior was more common than reported for solitary fibrous tumor of the pleura, but the same criteria (size, cellularity, mitotic activity, presence of pedicle) were of prognostic significance. The occurrence of solitary fibrous tumor in the mediastinum with the suggestion of thymic origin for some cases, combined with the immunohistochemical and ultrastructural findings, support a mesenchymal origin for this tumor. The differential diagnosis includes spindle cell thymoma, hemangiopericytoma, and peripheral nerve tumors.

In plain English

This article was a case series of 14 tumors in the mediastinum (the central chest area between the lungs). The authors judged them identical to solitary fibrous tumor of the pleura, also called so-called fibrous mesothelioma. The cases came from one author's consultation files. Patients were aged 27 to 70 (median 54). No patient had a known history of asbestos exposure. Eleven tumors were mainly in the anterosuperior mediastinum, and tumors measured 4.5 to 24 cm. Tumor cells stained for vimentin in seven of nine cases and for keratin in none of nine. Electron microscopy showed fibroblast-like cells with no sign of mesothelial or epithelial differentiation. Follow-up was available for 11 patients, and three died of disease. Of the followed tumors with sarcomatous areas, six of seven behaved aggressively, compared with one of four bland tumors. The authors noted that this aggressive behavior might reflect the biases of consultation material. They concluded the findings supported a mesenchymal (connective-tissue) origin for this tumor.

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 14 cases reviewed from pathology consultation files)
• Who was studied: 14 patients with a primary mediastinal solitary fibrous tumor, aged 27 to 70 (median 54), slight male predominance; cases contributed by pathologists at various hospitals to one author's consultation files
• Exposure: No asbestos exposure was studied; no patient had a known history of asbestos exposure
• Main results:
  • Eleven of the 14 tumors were located mainly in the anterosuperior mediastinum
  • Tumors ranged from 4.5 to 24 cm (median 13 cm) and weighed up to 1,610 g (median 600 g)
  • Tumor cells were positive for vimentin in seven of nine cases studied
  • Tumor cells showed no keratin immunoreactivity in any of nine cases studied
  • Electron microscopy in all nine cases examined showed only spindled mesenchymal cells consistent with fibroblasts
  • Follow-up was available in 11 of 14 cases. Three patients died of disease at 4 months, 2 years and 13 years after diagnosis
  • Among cases with follow-up, six of seven tumors with sarcomatous areas behaved aggressively, compared with one of four histologically bland tumors. None of the tumors smaller than 10 cm recurred
  • Aggressive behavior occurred in 64% of cases with follow-up, more than reported for pleural solitary fibrous tumor
  • Most tumors arose in a location compatible with thymic origin, and one clearly arose within thymic stroma
  • The authors stated that diagnostic and prognostic criteria for mediastinal solitary fibrous tumor were the same as for the pleural tumor
• The authors' conclusion: The authors concluded that the mediastinal location, the suggestion of thymic origin in some cases, and the immunohistochemical and ultrastructural findings supported a mesenchymal origin for this tumor.
• Limitations the authors state:
  • The higher rate of aggressive behavior may reflect the biases of consultation material

Topics

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

Medical terms in this study, explained in our Lexicon: Solitary Fibrous Tumor, Mediastinum, Neoplasm, Mesothelioma, Pleura, Dyspnea, Differential Diagnosis, Spindle Cell.

Related studies

• Solitary fibrous tumor of the mediastinum — N. Weidner (1991)
• A biphasic tumor of the mediastinum with features of synovial sarcoma. A report of four cases — G.B. Witkin, M. Miettinen, et al. (1989)
• Nuclear expression of STAT6 distinguishes solitary fibrous tumor from histologic mimics — L.A. Doyle, M. Vivero, et al. (2014)
• Cytopathological features of solitary fibrous tumor of the pleura: a study of 5 cases — B. Weynand, P. Collard, et al. (1998)
• Value of D2-40 in the differential diagnosis of pleural neoplasms with emphasis on its positivity in solitary fibrous tumor — Y. Hu, Q. Yang, et al. (2010)
• Solitary fibrous tumor of the upper respiratory tract. A report of six cases — G.B. Witkin, J. Rosai (1991)

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