[A case of metastatic lung tumor with multiple ground glass opacities on chest CT]

A 70-year-old man was admitted to our hospital because of multiple ground-glass opacities on his chest CT scan. A transbronchial lung biopsy specimen revealed signet-ring cell carcinoma infiltrating into the alveolar septa. The histological findings of the carcinoma obtained from the lung were very similar to those of his gastric carcinoma which had been resected at age 66. Immunohistochemical staining of the cancer cells were positive for keratin 7 and keratin 20, therefore a metastatic lung tumor from gastric cancer was diagnosed. Although multiple, well-defined nodules are typically considered to be the presentation of pulmonary metastases, clinicians should also be aware that multiple, ill-defined ground-glass opacities can also be recognized as pulmonary metastasis.