Abstract
Background : Primary signet-ring cell carcinoma of the lung is a rare tumor classified as a special subtype of adenocarcinoma under the WHO classification of lung cancer and the General Rule for Clinical and Pathological Record of Lung Cancer of the Japan Lung Cancer Society. We report herein on a case of primary signet-ring cell carcinoma of the lung.
Case : The patient was a 41-year-old woman who was found to have an abnormal shadow on chest X-ray at a regular medical checkup. Computed tomography revealed a mass in the lower lobe of the right lung. Since lung cancer was suspected, she underwent a bronchoscopic lung biopsy. Cytologic imprints of the biopsy specimen showed signet-ring tumor cells containing large amounts of a mucoid substance, suggesting mucin-producing adenocarcinoma. On immunohistochemical examination, the tumor cells were positive for CK7 and negative for CK20, and about half of them were positive for TTF-1. These findings led to a diagnosis of primary signet-ring cell carcinoma of the lung.
Conclusions : Primary signet-ring cell carcinoma of the lung is a rare tumor, but its possibility should be considered in conjunction with the examination of other organs when cytological specimens from lung tumors show signet-ring tumor cells containing mucin in the cytoplasm.
