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- Original Article -

Atypical Adenomatous Hyperplasia of the Lung Detected in a Thoracic CT Screening Program for Lung Cancer

Hiroyuki Takahashi¹⁾, Tohru Nakagawa²⁾, Ken Nawa²⁾, Youichi Sugawara²⁾, Katuyuki Endou³⁾, Noboru Yanai⁴⁾, Takatoshi Aoki¹⁾ and Hajime Nakata^1)
1)Department of Radiology, University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka, Kitakyushu, Fukuoka, Japan, ²⁾Hitachi Health Care Center, Hitachi Ltd, 4-3-16, Oose-chou, Hitachi, Ibaragi, Japan, ³⁾Hitachi General Hospital, Hitachi Ltd, 2-1-1, Jonancho, Hitachi, Ibaragi, Japan, ⁴⁾Seiranso Hospital, National Sanatorium, 825, Ooaza Terunuma, Tokai, Ibaragi, Japan

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Objective: To examine the HRCT findings and the frequency of atypical adenomatous hyperplasia (AAH) of the lung detected by CT screening for lung cancer. Subjects and Methods: During the period from April 1998 to November 1999, 7,980 persons (men 6,136, women 1,844, average age, 57 years old) underwent CT screening for lung cancer with low dose spiral CT. All CT scans were obtained with a RADIX Turbo (Hitachi Ltd, Tokyo, Japan). Screening CT consisted of 10 mm contiguous sections obtained with 120kVp and 50mA. HRCT with 2.0 mm sections, 120kVp and 150mA were performed one month thereafter on those who were suspected to have lung cancer. A total of 5 cases of AAH were pathologically confirmed among 5,991 initially screened subjects. These 5 cases are the basis of this study. Results: The size of AAH ranged in diameter from 7.9 to 12.4 mm (mean, 9.8 mm). All showed ground glass opacity on HRCT and none were visible on chest radiograph. Three cases did not change in size for 3-12 months. The frequency of AAH was 0.083% but it increased to 0.167% when cases suspicious on HRCT but not pathologically confirmed were included. Conclusion: Thoracic CT screening using low dose spiral CT is useful for detecting AAH which can be a clue for diagnosing an early curable lung cancer. All HRCT images of AAH showed localized ground glass opacity on HRCT and no change during observation before surgery.
key words: Atypical adenomatous hyperplasia, Lung cancer, Low dose spiral CT, Thoracic CT Screening

Received: September 4, 2000
Accepted: December 4, 2000

JJLC 41 (1): 21-25, 2001