Cytological features in eight patients with ALK-rearranged lung cancer

Background: ALK-rearranged lung cancer has been recently identified. Although signet-ring cell morphology and mucinous cribriform pattern are considered to be characteristic of ALK-rearranged lung cancer. Some studies have also suggested cytological features. Methods: This study investigated cytological features of ALK-rearranged lung cancer in eight patients. Results: Cytologically, the tumor cell group varied from isolated to large clusters. Small nucleoli, fine granular to vesicular chromatin, and nuclear groove were observed in all patients. Furthermore, extracellular and intracellular mucin and signet-ring cells were identified in five patients. Conclusion: This study demonstrated that the presence of extracellular and intracellular mucin, signet-ring cells, small nucleoli, fine granular to vesicular chromatin, and nuclear groove in cytological samples may be a diagnostic clue for ALK-rearranged lung cancer.