Small lung tumors with the size of 1cm or less in diameter: clinical, radiological, and histopathological characteristics.

BACKGROUND

The detection rate of small nodules in the peripheral lung area is increasing due to the widespread use of CT scanning. However, the radiological and pathological characteristics of very small tumors have not been fully investigated.

METHODS

We evaluated 44 lung tumors with the size of 1cm or less in diameter resected from 38 patients (19 men and 19 women, with an average of 62 years) from 1997 through 2001. The clinical records, the findings of high-resolution CT (HRCT) and histopathological features of resected specimens were analyzed. Adenocarcinoma was histologically further subclassified into types A to F according to the Noguchi's classification.

RESULTS

Lobectomy was performed in 20 patients, wedge resection in 15 and segmentectomy in 3, respectively. Thirty-two tumors were adenocarcinomas, 4 were squamous cell carcinomas, and eight were atypical adenomatous hyperplasia (AAH), respectively. All carcinoma cases were proved to be stage IA. In adenocarcinoma, type A was detected in 12 tumors, type B in 13, type C in 1, type D in 2, type E in 1, and type F in 3, respectively. Most of AAH and type A showed pure ground-glass attenuation on HRCT scan, whereas types B to F as well as squamous cell carcinoma frequently had malignant CT signs such as lobulation and convergence of peripheral vessels. Lymphatic or vascular invasion was observed in two adenocarcinomas (types D and F) and two squamous cell carcinomas, and HRCT scan of these four tumors showed soft-tissue attenuation occupying more than two-thirds of each nodule. All patients are currently alive without signs of recurrence after a mean follow-up period of 35.5 months.

CONCLUSION

Types A and B of adenocarcinoma were the most common histologic types among lung tumors with the size of 1cm or less in diameter. Limited lung resection appears to be an adequate for such small lung tumors in which soft-tissue attenuation consists of less than two-thirds of the nodule on HRCT.