Desmoplastic malignant mesothelioma masquerading as sclerosing mediastinitis: a diagnostic dilemma

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.