2021 Volume 48 Issue 5 Pages 241-247
Purpose: Histological classification of breast tumors edited by the Japanese Breast Cancer Society was revised in 2018. The purpose of this study was to clarify the impact of the revision on diagnostic imaging of invasive ductal carcinomas. Subjects and Methods: We investigated ultrasound images of 91 cases diagnosed as papillotubular carcinoma of invasive ductal carcinoma according to the old classification. Results and Discussion: The histological subtypes according to the new classification were microinvasive carcinoma in 26 cases (28.6%), invasive carcinoma with a predominant intraductal component in 51 cases (56.0%), and tubule forming type of invasive ductal carcinoma in 14 cases (15.4%). Ultrasound imaging showed a mass in 41 cases (45.1%) and a non-mass lesion in 48 cases (52.7%). In the remaining two cases, ultrasonography could not detect any abnormal findings. Of the microinvasive carcinoma cases, 19 cases (73.1%) showed a non-mass lesion that mimicked ductal carcinoma in situ. Ultrasound imaging of the cases diagnosed as invasive carcinoma with a predominant intraductal component revealed a mass in 22 cases (43.1%) and a non-mass lesion in 27 cases (52.9%). Twelve (85.7%) of the 14 cases with tubule forming type showed a solid mass. Of these, seven cases (58.3%) revealed discontinuity of borderline between mammary gland and fat tissue, suggesting invasive carcinoma. Papillotubular carcinomas showing various ultrasound images were divided into three histological types by the new classification, and each type showed characteristic ultrasound images. Conclusion: The new classification enables breast tumors to be correctly diagnosed by means of imaging.
