Unusual Thoracic Problems in Patients With Malignancies

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A 45-year-old white male was diagnosed with pulmonary alveolar proteinosis (PAP) when he was 31 years old. He was treated with periodic bronchoalveolar lavage to remove large volumes of proteinaceous material from his lungs (last lavage in December 2002). In September 2003, he presented with a 6-week history of right-sided pleuritic chest pain, progressive shortness of breath, and weight loss of 14 kgs over the previous 2 months. Chest radiographs revealed bilateral alveolar infiltration with a right pleural effusion. Initial computed tomography of the chest showed bilateral air-space disease, and a right pleural effusion. There was no pleural thickening or lymphadenopathy. At thoracentesis, 1,500 mL of hemorrhagic pleural fluid was removed. The fluid reaccumulated in 48 hours, requiring a video-assisted thoracoscopy, drainage, and pleurodesis with talc. At thoracoscopy, a 3-cm mass was seen in the superior segment of the right lower lobe, and pleural implants were biopsied. He was referred to our facility with a diagnosis of malignant mesothelioma. The patient was a nonsmoker with no family history of cancer or exposure to asbestos. On examination, he was using oxygen at 2 l/min. His breath sounds were diminished on the right side. A repeat computed tomography scan (Figs 1A and 1B) showed pleural implants, areas of PAP, as well as a mass in the right lung with hilar adenopathy. Pathologic exam (Figs 1C and 1D) revealed clusters of malignant mesothelial cells that were strongly positive for calretinin stain, consistent with a diagnosis of malignant mesothelioma. Treatment for mesothelioma was instituted with chemotherapy consisting of cisplatin and pemetrexed on an expanded-access program. The patient has had a marked decrease in the mass and adenopathy, and no longer required oxygen after two cycles of chemotherapy. PAP is a rare condition with an estimated annual incidence and prevalence of 0.36 and 3.70 cases per million population, respectively. This disorder is a disease of alveolar macrophage dysfunction caused by excessive intraalveolar surfactant accumulation. The signaling pathways in these macrophages are turned on by granulocyte-macrophage colony-stimulating–factor. PAP has been described in association with congenital disorders, immunodeficiency states, hematologic malignancies, myelodysplastic syndrome, infection with Pneumocystis carinii, and inorganic dust exposure. There are no previously reported cases of PAP associated with mesothelioma. However, changes resembling those of alveolar proteinosis have been reported in the lung adjacent to