Diagnostic ultrasound ( PDFDrive )

792 PART III Small Parts, Carotid Artery, and Peripheral Vessel Sonography
D
T
* * *
T
T
D
D
A B C
FIG. 21.46 Terminal Ductolobular Unit (TDLU) Carcinoma. Taller-than-wide orientation corresponds to a small, in situ or invasive carcinoma
involving a single TDLU. (A) Normal lobule (*), its extralobular terminal duct (T), and part of the segmental duct (D). The TDLU orientation is taller
than wide. (B) Small, intermediate–nuclear-grade ductal carcinoma in situ (DCIS) grossly distends the lobule and its extralobular terminal duct,
remaining oriented in the taller-than-wide axis of the lobule from which it arose. (C) Small, low–nuclear-grade invasive ductal carcinoma more
grossly distends and distorts the lobule and extralobular terminal duct from which it arose, but remains oriented taller than wide. Note the angles
that indicate invasion into the surrounding tissues.
* *
RT 12 2B RAD
#
# FIG. 21.48 Duct Extension of Ductal Carcinoma in Situ (DCIS). DCIS
growing within the lobar duct toward nipple. Most invasive duct carcinomas
contain DCIS components. In some cases the DCIS growing
away from the tumor toward the nipple within the lobar duct may grossly
distend the duct enough to allow recognition of duct extension sonographically
(arrows). If such duct extensions are not recognized on ultrasound,
they might be transected at surgery, leading to positive margins, local
recurrence, and the need for reresection.
FIG. 21.47 Ductal Carcinoma in Situ (DCIS). Growth of DCIS
changes shape to parallel. As malignant solid nodules enlarge, DCIS
components grow down the lobar duct toward the nipple and develop
cancerized adjacent lobules, changing from not parallel to parallel shape.
Tumor-distended anterior lobules (*); tumor-distended but smaller posterior
lobules (#); and tumor-distended lobar duct (arrows) are shown.
and invasive lobular carcinomas also tend to cause either acoustic
shadowing or enhanced sound transmission.
he diferential diagnosis for malignant masses that cause
acoustic shadowing, in order of frequency, consists of (1) lowgrade
to intermediate-grade invasive ductal carcinoma, (2) invasive
lobular carcinoma, (3) tubulolobular carcinoma, and (4) tubular
carcinoma. he diferential diagnosis for malignant masses
associated with enhanced sound transmission includes high-grade
malignancies, colloid carcinoma, medullary carcinoma, and
invasive papillary carcinoma. 51-55
Hypoechogenicity
Hypoechogenicity is a subcategory of the ACR BI-RADS category
“Echo Pattern.” 17 Marked hypoechogenicity of the substance of
a solid mass (compared with fat) is a mixed suspicious internal
characteristic sonographic feature of malignancy. It can be the
result of several diferent tumor characteristics. High-grade
invasive ductal carcinomas that are highly cellular and contain
abundant hyaluronic acid in the extracellular matrix may appear
hypoechoic because of the high water content. Pure DCIS may
appear hypoechoic because of either necrosis or secretions within
the lumina of tumor-distended ducts. Low-grade invasive ductal
carcinomas can appear “markedly hypoechoic” because of acoustic