Multiple Pulmonary Tumor Embolisms Showing Radiographic Findings Similar to Interstitial Lung Disease in a Patient with Bladder Cancer

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Background. Tumor embolism is one of the manifestations of pulmonary metastasis, but is difficult to diagnose before death because the imaging features are nonspecific and biopsy is necessary to confirm diagnosis. Most lung tumor embolisms are confirmed at autopsy. Case. A 51-year-old man with advanced bladder cancer who was treated with chemotherapy developed dyspnea on effort. Chest CT image demonstrated linear, reticular and ground-glass opacity and dilation of pulmonary arteries. Pulmonary tumor embolism was suspected, however, drug-induced interstitial lung disease also had to be considered in the differential diagnosis. A transbronchial lung biopsy (TBLB) revealed tumor cells in small lung blood vessels, indicating pulmonary tumor emboli. The clinical presentation of this patient made it difficult to distinguish his condition from interstitial lung disease, and TBLB was useful in diagnosis. Conclusion. Microscopic pulmonary tumor embolism should be considered in the differential diagnosis of a patient with cancer who presents with worsening dyspnea or with abnormal shadows emerging on chest radiographs. The present case showed that when an abnormal interstitial shadow is identified on a chest radiograph and on a CT scan of a patient undergoing chemotherapy for malignancy, TBLB can prove useful in differentiating drug-induced pulmonary disease from tumor progression, such as tumor embolism.