Abstract
Background. Signet ring cell carcinoma is commonly associated with gastric cancer, and rarely affects other organs. Case. A 78-year-old male visited a hospital because his left neck was swollen. A needle biopsy was performed, and the findings of the cervical lymph nodes proved to be consistent with signet ring carcinoma cells. The tumor cells were immunohistochemically stained positive for CK7, CEA and MUC5AC, and negative for PSA, TTF-1, CK20 and CD10. A PET-CT scan showed diffuse accumulation in the stomach, a lung nodule in the right lower lobe and in lymph nodes in the mediastinum. Gastroscopy, bronchoscopy and colonoscopy were all performed, but only revealed the presence of a "well differentiated carcinoma in the stomach", that did not correspond to metastasis from signet ring cell carcinoma. The patient underwent chemotherapy with both carboplatin (CBDCA) and docetaxel (DTX) for five months, but suffered from disease progression, with new lesions found in the liver and lungs. Next, the patient received second-line chemotherapy with S-1, an orally available agent, but he rapidly developed renal failure, and soon died. We were given permission to perform an autopsy, which revealed the presence of signet ring cells in the lymphatics of the lung, metastatic lymph nodes in the hilar and mediastinal regions, pleural effusion, pericardial effusions and liver metastases. However, we were unable to define the primary origin of the tumors. Conclusion. We herein reported a case of signet ring cell carcinoma of unknown origin. The distinct primary site could not be found, even by autopsy.
