Malignant Pleural Effusion and Osteoblastic Metastases as the Initial Manifestation of Occult Gastric Cancer

A 53-year-old man was admitted to our hospital because of lumbago. Gastrointestinal endoscopic examination performed on admission did not reveal any gross gastric abnormalities. Lumbar radiography and bone scintigraphy revealed multiple bone osteoblastic changes. Chest radiography showed right pleural effusion. The findings of the chest computed tomography and cytological examination of the pleural effusion were strongly suggestive of lung cancer. The patient was refractory to chemotherapy, and he died of cancer and disseminated intravascular coagulation. The autopsy revealed absence of primary lung cancer and the presence of tumor emboli in the right lung field. Swollen perigastric lymph nodes, tiny signet-ring cell carcinoma at the posterior wall of the stomach corpus, and severe vascular invasion were also observed at autopsy. Therefore, signet ring cell carcinoma of the stomach should be considered as a possible diagnosis in early-stage gastric cancer patients who develop osteoblastic metastasis and pleural effusion.