Diagnostic value of string beads sign in peripheral small cell lung cancer / 实用放射学杂志

ABSTRACT

Objective To investigate the formation mechanism of string beads sign in peripheral small cell lung cancer (SCLC) and evaluate the significance of it in differential diagnosis among SCLC,peripheral lung adenocarcinoma and peripheral lung squa-mous cell carcinoma.Methods 78 cases of SCLC,69 cases of peripheral lung adenocarcinoma and 33 cases of peripheral lung squa-mous cell carcinoma,confirmed pathologically were included in this study.The positive rates of string beads sign,mediastinal lymph node metastasis and mediastinal lymph nodes larger than primary lung lesions were calculated and analyzed in these three groups.Results 10 out of SCLC cases (12.8%)have string beads sign,in which all mediastinal lymph nodes were larger than lung lesions.Mediasti-nal lymph node metastases were observed in 63(80.8%)of 78 cases,and 42 (53.8%)cases had larger mediastinal lymph nodes than lung lesions.No string beads sign was observed in patients with peripheral solid lung adenocarcinomas,but 25 of 69 cases (36.2%) have mediastinal lymph node metastasis and 2 cases (2.9%)had larger mediastinal lymph nodes than lung lesions.13 cases(39.4%) of 33 patients with peripheral lung squamous cell carcinomas had mediastinal lymph node metastasis,and 6 cases (16.7%)had larger mediastinal lymph nodes than lung lesions.The statistical results showed the positive rate of string beads sign was not significantly different between peripheral SCLC group and peripheral lung squamous cell carcinoma group,but that of mediastinal lymph node and larger mediastinal lymph nodes than lung lesions were statistically different among these three groups.Conclusion To some extent, string beads sign on CT could reflect the biologic character of SCLC.It played an important role in differential diagnosis of peripheral SCLC,peripheral lung adenocarcinoma and periph-eral lung squamous cell carcinoma,but it should be combined with mediastinal lymph node size.