Diagnostic ultrasound ( PDFDrive )

CHAPTER 21 The Breast 791
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A
B
C
D
FIG. 21.45 Microlobulations. These can represent either angles of invasive tumor or ductal carcinoma in situ (DCIS) components of the lesion.
(A) When microlobulations are pointed or angular (arrows) and associated with spiculations or thick, echogenic rim (*), they represent ingers of
invasive tumor. (B) When microlobulations appear as small “tennis rackets” (arrows) projecting from the surface of the nodule, they represent
surrounding lobules distended with DCIS or cancerous lobules. Microlobulations that are round or oval with thin, echogenic capsules represent
tumor-distended ducts. The thin capsule represents the intact duct wall. (C) Small microlobulations (arrows) correspond to minimally distended
ducts that are illed with low–nuclear-grade DCIS. (D) Large microlobulations (arrows) correspond to grossly distended ducts that contain high–nucleargrade
DCIS.
he presence of duct extension is not a speciic sign of
malignancy, but rather suggests an intraductal growth pattern.
Benign intraductal lesions such as papillomas and chronic
periductal mastitis and ibrosis can also demonstrate duct extension.
Overall, it is important to recognize duct extension for two
reasons: (1) to minimize false-negative characterization of pure
DCIS and (2) to identify extensive intraductal components of
tumor.
Acoustic Shadowing
Acoustic shadowing is a subcategory of the ACR BI-RADS
category “Posterior Features.” 17 Acoustic shadowing is a hard
suspicious internal characteristic inding that suggests the presence
of invasive malignancy. Acoustic shadowing tends to occur in
solid nodules that lie on the spiculated end of the malignant
spectrum and represent about one-third of all solid malignant
nodules. he desmoplastic components of the tumor substance
and spiculations cause the shadowing (Fig. 21.49). Because breast
carcinomas can be internally heterogeneous, only part of a solid
malignant nodule might give rise to acoustic shadowing. Other
parts of the lesion might be associated with normal or enhanced
sound transmission. High-grade invasive ductal carcinomas,
the most common circumscribed malignant nodules, do not
usually cause shadowing. In fact, they most oten have associated
enhanced sound transmission (Fig. 21.50A). Even pure DCIS that
is high nuclear grade may be associated with enhanced through
transmission. Many intermediate-grade lesions demonstrate
normal sound transmission (Fig. 21.50B). Special-type tumors