lobule
noun [ C ] medical specialized uk/ˈlɒb.juːl/ us/ˈlɑːb.juːl/
（器官）小叶
a small lobe (= a part of an organ that seems to be separate from the rest)
Breast cancer forms in breast tissue, commonly arising in the ducts or lobules. 乳腺癌出现在乳房组织中，通常发生在导管和小叶中。