[Differential diagnosis of focal areas of ground-glass attenuation in the peripheral lung 20 mm or less in diameter: high-resolution CT-pathologic correlation].

BACKGROUND

The detection and differential diagnosis of focal areas of ground-glass attenuation (FGGA) is becoming important for early diagnosis of lung cancer.

PURPOSE

The purpose of this study is to clarify the correlation between FGGA (20 mm or less in diameter) on high-resolution CT (HRCT) and histopathology of surgically resected lesions.

MATERIALS AND METHODS

Ninety surgically resected peripheral lung lesions 20 mm or less in diameter with a greater than 50% area of GGA on HRCT from 58 patients (34 men and 24 women; mean age, 60.5 years) were studied. Sixty-nine lesions were adenocarcinomas (type A; 31, type B; 5, type C; 32, type D; 1, according to Noguchi et al.), 11 were atypical adenomatous hyperplasias, and 10 were inflammatory lesions. HRCT findings were retrospectively evaluated with regard to maximum diameter, marginal character, internal dense attenuation domain, and linear density radiating into surrounding lung parenchyma. Statistical analysis was performed with Mann-Whitney's t-test, Pearson's correlation coefficient, and chi 2-test between each group of lesions.

RESULTS

The maximum diameters on HRCT were significantly larger in adenocarcinomas (mean, 12.7 +/- 5.5 mm) than in atypical adenomatous hyperplasias (4.6 +/- 1.9 mm, p < 0.01) and in inflammatory lesions (5.9 +/- 2.7 mm, p < 0.01). Among adenocarcinomas, the diameters of type C tumors (mean, 15.7 +/- 5.0 mm) were larger than those of type A tumors (9.0 +/- 3.1 mm, p < 0.01). Linear density radiating into surrounding lung parenchyma was not found in inflammatory lesions, atypical adenomatous hyperplasias or type A tumors. Dense attenuation domains were found more frequently in type C tumors (94%) than in type A or type B tumors. Linear density and dense attenuation domain were both correlated with size of lesion (p < 0.05, p < 0.01, respectively).

CONCLUSIONS

HRCT is useful in the diagnosis of early pulmonary adenocarcinomas presenting as small FGGA.