62-year-old male, asbestos exposure 30 years ago, 1-year history of dyspnoea. Autopsy specimen.
Macroscopically: The compressed lung lobe is covered by a whitish tumor.
- Markedly thickened pleura with attached lung tissue
- The visceral and parietal pleura cannot be distinguished.
- The tumour infiltrates the lungs, chest wall and can be found throughout the pleura.
- The tumour is composed of 1. epithelial part: tubulopapillar or adenomatous, partly solid cell strands consisting of middle-sized to large, often cuboid polymorphic cells
2. sarcomatous cells: spindle-shaped tumour cells with polymorphism, atypia and mitosis, sometimes in bundles arranged in whirls
- Subpleural interstitial fibrosis of the lung
Differential diagnosis: non-neoplastic, cell-rich stroma appearing as sarcomatous component. Without special stains the epithelial component cannot be distinguished from pleural carcinosis of adenocarcinoma. The spindle-shaped component of the tumour morphologically corresponds to any other spindle-cell-shaped sarcoma. In the given specimen the diagnosis of mesothelioma can be made as there is an epithelial as well as a spindle-cell (sarcomatous) component.