A case of malignant pleural mesothelioma.

A 48-year-old male with history of hypertension, S/P thoracic aneurysm and aortic valve repair, presented with increasing shortness of breath. A chest CT showed extensive pleural thickening, right pneumothorax with pulmonary vein compression and left mediastinal deviation. A firm white area of pleural thickening covering the right lung was identified on the open lung biopsy. The patient was not known to have asbestos exposure. Routine hematoxylin and eosin stained sections were examined. Special stains included various immunoperoxidase and histochemical stains. Histologic examination demonstrated epithelioid cells arranged in papillae, cords and solid nests. The cells had uniform nuclei, prominent nucleoli and abundant eosinophilic cytoplasm. Frequent mitoses and skeletal muscle invasion were seen. The malignant cells were immunopositive for calretinin and immunonegative for B72.3, Ber-Ep4, TTF-1, and BRST-2. Ferruginous bodies and intracytoplasmic mucin were not identified. These findings were consistent with malignant mesothelioma. Pleural mesothelioma is a rare malignant tumor that is increasing in incidence. Asbestos exposure remains the major risk factor, found in 72-90% of patients. The most common symptoms of pleural mesotheliomas are malignant pleural effusion, dyspnea and chest pain. We report a case of a patient with severe cardiovascular disease, complicated by tension pneumothorax, and subsequent cardiopulmonary insufficiency resulting in a rapid demise. The patient's comorbidities masked the underlying malignant mesothelioma and made the diagnosis with FNA cytology difficult. In patients with underlying cardiopulmonary problems and a history of thoracic surgery, these symptoms along with pleural thickening on the chest X-ray, can be misinterpreted as secondary to postoperative change. Cytologic examination of pleural fluid is only diagnostic in 52-60% of pleural mesotheliomas. In one study the sensitivity was shown to be only 32%. Persistent pleural effusion with negative pleural cytology should raise a possibility of coexisting mesothelioma. Open lung biopsy remains the gold standard for the diagnosis.

Armine Baltayan, MD, Candice Frederick, MD, Karlene Hewan-Lowe, MD, and Cristian Robiou, MD. ECU/Brody School of Medicine, Greenville, NC.