Abstract

Purpose: To evaluate the significance of the bronchial cast sign (BCS) and the string of beads sign (SBS) in the differential diagnosis among peripheral small cell lung cancer (pSCLC), peripheral lung adenocarcinoma (pLUA) and peripheral lung squamous cell carcinoma (pLSCC).

Methods and materials: Pathologically confirmed 78 cases of pSCLC, 69 cases of pLUA and 33 cases of pLSCC were included in this study. The positive rates of BCS, SBS, and mediastinal lymph node metastasis and mediastinal lymph nodes larger than primary lung lesions were calculated and analyzed in the groups of pSCLC, pLUA and pLSCC, respectively.

Results: In the 78 pSCLC patients, the positive rate of BCS, SBS, mediastinal lymph node metastasis and mediastinal lymph nodes larger than primary lung lesions were 23.1%, 12.8%, 80.8% and 53.8%, respectively. Mediastinal lymph nodes were all larger than primary lung lesions in the pSCLC cases with SBS. There were no BCS or SBS observed in the 69 cases of pLUA, in which 25 cases (36.2%) had mediastinal lymph node metastasis and 2 cases (2.9%) shown the mediastinal lymph nodes were larger than the original lung lesions. The positive rates of BCS, SBS, mediastinal lymph node metastasis and mediastinal lymph nodes larger than primary lung lesions were 6.1%, 2.8%, 39.4% and 16.7% of the total 33 pLSCC patients, respectively.

Conclusion: SBS and BCS in CT images reflect the biologic characters of pSCLC at a certain level and show noteworthy clinical value in differential diagnosis of pSCLC, pLUA and pLSCC. However, the two signs should be combined with other CT signs of pSCLC and mediastinal lymph node.