Desmoplastic malignant mesothelioma masquerading as sclerosing mediastinitis: a diagnostic dilemma

Our plain-English summary of Desmoplastic malignant mesothelioma masquerading as sclerosing mediastinitis: a diagnostic dilemma, by T.B. Crotty, T.V. Colby, P.C. Gay, et al (Human Pathology, 1992).

The study

• Authors: T.B. Crotty, T.V. Colby, P.C. Gay, R.J. Pisani
• Journal: Human Pathology
• Published: 1992;23(1):79-82
• Type of article: Case report
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A 48-year-old woman presented with dyspnea, chest discomfort, and left vocal cord paralysis that developed 2 months after a flu-like illness. Radiographic examination showed prominence of mediastinal soft tissues and an ill-defined left upper lobe infiltrate. Dense mediastinal sclerosis was found at thoracotomy, and biopsy samples taken from the sclerotic areas showed densely hyalinized fibrotic tissue. Necrotizing granulomas containing organisms resembling Histoplasma capsulatum were present within mediastinal lymph nodes. Based on these findings, a diagnosis of sclerosing mediastinitis was made. During the next year, the patient's respiratory function deteriorated, and biopsy samples taken during a second thoracotomy 1 year later were again interpreted as sclerosing mediastinitis. The patient died postoperatively; at autopsy, the sclerotic mass involving the mediastinum was composed of a mixture of dense fibrosis and sarcomatous tissue. The final diagnosis was localized mediastinal desmoplastic malignant mesothelioma. We report it here because of its unusual clinical presentation, which mimicked sclerosing mediastinitis.

In plain English

This article was a case report about one woman from Iowa with no history of significant asbestos exposure. Her symptoms, including chest discomfort, shortness of breath and vocal cord paralysis, matched typical features of sclerosing mediastinitis, a scarring condition of the central chest. At a first chest operation, surgeons found a dense scarring process. Lymph nodes held granulomas consistent with past infection by the fungus Histoplasma capsulatum. The authors believed these were an incidental finding. It was still thought to be sclerosing mediastinitis after a second chest operation. At autopsy, mediastinal tissue showed high-grade sarcomatous areas, and the features were typical of desmoplastic malignant mesothelioma. Strong keratin staining excluded a mediastinal sarcoma, and negative stains argued against spindle cell carcinoma. No asbestos bodies were found in iron-stained sections of lung tissue. The authors wrote that keratin staining of the bland, fibroblast-like cells suggests the correct diagnosis could have been made at the first biopsy had this tumor been considered. They cautioned that many benign pleural lesions also stain for keratin, and that the staining pattern of sclerosing mediastinitis had not been specifically studied.

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 (single patient)
• Who was studied: One woman living in Iowa, evaluated from February 1988, with no history of significant asbestos exposure
• Exposure: No history of significant asbestos exposure was reported; no fiber type was studied
• Main results:
  • The patient's symptoms were typical presenting features of sclerosing mediastinitis
  • At the first thoracotomy a dense sclerosing (scarring) process was found
  • Granulomas showed a previous infection consistent with Histoplasma capsulatum, which the authors considered incidental
  • The lesion was thought to be sclerosing mediastinitis, clinically and pathologically, even after a second thoracotomy
  • At autopsy, mediastinal tissue showed high-grade sarcomatous differentiation, and the features were typical of desmoplastic mesothelioma
  • Strong keratin staining excluded mediastinal sarcoma; negative staining for mucins, carcinoembryonic antigen and Leu-M1 argued against spindle cell carcinoma
  • Asbestos bodies were not present in iron-stained sections of lung tissue (OCR-damaged passage)
• The authors' conclusion: The authors wrote that positive keratin staining of the bland fibroblast-like cells suggests the correct diagnosis could have been made at the first biopsy if desmoplastic malignant mesothelioma had been considered. They also cautioned that benign reactive pleural lesions can stain for keratin.
• Limitations the authors state:
  • Many benign reactive pleural lesions also stain positively for keratin, and the immunohistochemical profile of sclerosing mediastinitis had not been specifically examined

Topics

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

Medical terms in this study, explained in our Lexicon: Desmoplastic Mesothelioma, Malignant Mesothelioma, Dyspnea, Thoracotomy, Biopsy, Granuloma, Mediastinal Lymph Nodes, Autopsy.

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