Abstract

Here, we report an exceedingly rare case of pulmonary cancer, composed of more than 70% Signet Ring Cells (SRC) in a Japanese male in his early 70s. Computed tomography detected the tumor shadow in the right lower lobe of the lung revealing a size of 1.1 cm × 0.7 cm × 0.7 cm. The SRCs were positive for Cytokeratin 7 (CK7), Thyroid Transcription Factor-1 (TTF-1), and Anaplastic Lymphoma Kinase (ALK).

The presence of SRC indicates one of the worst prognostic factors for patients with pulmonary cancer, based on the statistical analysis of ALK-positive cases. The possibility of the 5 year survival was reported to be only 11%. The anti-ALK inhibitor crizotinib has been applied in practical clinical therapy and obtained partial remission. However, drug resistance is exhibited in SRC cancer. This is a significant concern for future clinical application of the drug for this type of lung cancer that exhibits poor prognosis. However in our report, no recurrence or distant metastasis was detected in the patient 15 months after operation despite not using crizotinib.

Finally, the composition of SRC in lung cancer should be considered for the patient’s prognosis, especially when ALK-positivity is detected.

Keywords: Pulmonary cancer; Signet ring cell carcinoma; Histopathology; Immunohistochemistry; ALK-positivity