Objective: Cytologic micropapillary clusters (MPCs) are round, three-dimensional and cohesive clusters of lung cancer cells with a pseudopapillary configuration. Recently, we demonstrated that MPCs from early stage lung adenocarcinomas can be considered as useful aids to assessing prognosis. We here demonstrate that stage I lung adenocarcinomas found to be positive for MPCs in preoperative cytologic approaches are high risk for lymphatic spread.
Methods: The clinicopathologic characteristics, metastatic status of dissected lymph nodes, vascular infiltration and presence of MPCs in preoperative cytologic specimens in 209 patients with clinical stage I lung adenocarcinomas undergoing complete surgical resection during 2004-2006 were reviewed.
Results: Thirty-eight patients (18%) had positive MPC findings; 21 patients with clinical stage IA and 17 with stage IB. Significant associations with postoperative stages IA and IB, frequent lymph node metastasis and venous infiltration on pathologic examination were observed (P<0.05). In particular, 50% of clinical stage I patients with MPCs demonstrated advance in the postoperative stage of disease.
Conclusions: MPCs may be a manifestation of aggressive behavior, as evidenced by frequent lymph node metastasis, of clinical stage I lung adenocarcinomas. Preoperative cytologic detection of MPCs, therefore, should alert the surgeon to the probability of lymph node metastases.