Diagnostic ultrasound ( PDFDrive )

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FIG. 21.8 Terminal Ductolobular Units (TDLUs). The TDLU includes the extralobular terminal duct and the lobule, which contains the intralobular
terminal duct, ductules, and intralobular isoechoic loose stromal tissue. TDLUs appear as an isoechoic structure similar to a tennis racket; the head
of the racket (*) represents the lobule, and the handle and neck of the racket (arrows) represent the extralobular terminal duct. Bottom center
image is three-dimensional histology. (Courtesy of Hanne M. Jensen, MD.)
A
RT 1200 2B AR N 4, 5
B
RT 900 3B AR N 5, 6
C
LT 100 2B RAD N 3, 4
D
FIG. 21.9 Variable Prominence of Terminal Ductolobular Units (TDLUs). (A) Only a few scattered TDLUs may be visible. (B) As TDLUs
become larger and more numerous in adenosis and adenosis of pregnancy, they may almost touch each other. Because anterior TDLUs are more
numerous than posterior TDLUs, these changes tend to affect the supericial aspect of the mammary zone earlier and to a greater extent than
they affect its deep aspect. (C) When lobular enlargement is pronounced, the entire supericial aspect of the mammary zone may appear isoechoic,
with the deep half still being hyperechoic. (D) When lobular prominence is most pronounced, both supericial and deep aspects of the mammary
zone may appear almost homogeneously isoechoic.