Ductal Carcinoma
In Situ
381
for consultation, Lennington et al.
115
recorded size from the
“outside surgical pathology report” for “extensive lesions”
but for “smaller, less extensive lesions, size was measured di-
rectly from the glass slides.” Lesions 2 mm or less in diame-
ter were excluded by definition, because they were classified
as atypical hyperplasia. The authors stated that they “. . . rec-
ognize the lack of precision, but believe the measurements
are usually within 3–5 mm of true extent. There is probably
a greater error in larger lesions.” This range of error in mea-
suring the size of DCIS is a further impediment to using le-
sion size as a criterion for distinguishing hyperplasia from
DCIS. In the face of these substantial limitations, the authors
reported the following distribution of “precise” mean sizes
in relation to histologic subtype: all pure DCIS exclusive of
micropapillary, 8.5 mm; mixed noncomedo histologic types,
13.1 mm; noncomedo with necrosis, 11.6 mm; comedo,
16.2 mm; and micropapillary, 19.1 mm.
115
The terms “extensive” intraductal component or “exten-
sive” intraductal carcinoma should not be used as synonyms
for widespread DCIS, as these terms have a different clinico-
pathologic connotation. “Extensive” DCIS ought to be used
only when DCIS is associated with invasive carcinoma, and
the DCIS therein, constituting more than 25% of the tumor
mass, extends beyond the dominant tumor mass into adja-
cent breast parenchyma.
In sum, sequential sectioning of surgical specimens (opti-
mally conducted with radiologic correlation) is essential for
the precise assessment of the extent of DCIS. The consistent
practice of sampling in this manner will also optimize ob-
servational research on issues relating to size and margins.
MULTICENTRICITY AND MULTIFOCALITY
There is no uniformly accepted definition of
multicentric-
ity
in DCIS. The concept of multicentricity was advanced
by Cheatle and Cutler,
10
Cheatle,
270
and Charteris
271
as a
result of observations made on whole-organ sections of
mastectomy specimens. Carcinoma was considered to be
multicentric when there were foci that were separate from
the clinically detected tumor. Lagios et al.
272
defined mul-
ticentricity as “ the presence of separate independent foci
of carcinoma within the breast—separate from the lesion
which is clinically or mammographically evident, that is, the
reference tumor.”
Multicentric DCIS is generally defined as that present in
multiple quadrants.
273–276
The use of this definition for the
term precludes its use in routine lumpectomy specimens,
unless the term is used for DCIS separated by 5 cm or some
other arbitrary dimension. The rate of multicentricity of
DCIS has traditionally been stated to be approximately 25%,
with a range from 0% to 75% or so, such a wide range that
reflects differences in the definition of the term. For practi-
cal purposes, multicentricity refers to foci of carcinoma in
distinctly different regions of the breast, usually in two or
more quadrants.
Multicentricity should be distinguished from in-
traepithelial extension within ducts and lobules of a
increased with the nuclear grade of DCIS on mammogra-
phy, and it increased as the mammographic breast density
decreased.
264
Although preoperative imaging has limitations
in determining the extent of DCIS, specimen slice radiogra-
phy can improve these estimates.
265
It is sometimes possible to determine the size of a lesion
microscopically if it is limited to a single group of contiguous
ducts (unifocal), especially when the area is confined to the
histologic section froma single paraffin block that contains tis-
sue from an excisional biopsy. Reporting the size of the small
lesions in this category is confounded by the fact that some
authors exclude abnormalities smaller than 2 mm from the
diagnosis of DCIS regardless of histologic appearance.
115,266
A significant proportion of DCIS are multifocal and not
confined to a single coherent palpable lesion or to a micro-
scopic focus that will fit in the confines of a single paraffin
block. It is noteworthy that the dimensions of a DCIS limited
to one standard paraffin block would not ordinarily exceed
2.0 to 2.5 cm or approximately 1 inch. Lagios et al.
267
studied
mastectomy specimens from patients with DCIS by a serial
subgross method and reported that the frequency of multi-
centricity and occult invasion was substantially greater for
lesions larger than 2.5 cm. It is on the basis of these studies
that 2.5 cm came to be viewed as an important size criterion
in the selection of patients for breast-conserving therapy. La-
gios
268
expressed skepticism about the quantitation of DCIS,
observing that “quantitation of DCIS will remain a problem
since the association of the extent of DCIS, and the extent of
microcalcifications, the only preoperative measure available
at present, is quite variable.”
Presently, there is no consensus on a method for deter-
mining the extent of DCIS on the basis of the proportion
of slides showing the lesion. This approach is highly depen-
dent on the completeness of sampling and biopsy size, both
of which determine the denominator. This issue would be
partially addressed if the denominator were biopsy weight in
grams with the numerator representing the number of slides
showing DCIS. This calculation would be most useful in
situations where all tissue has been processed for histologic
examination. Until a standardized method has been vali-
dated and widely adopted, the number of sections involved
in sequentially taken samples (or at a minimum the propor-
tion of slides with DCIS) will remain a crude measure of the
extent of DCIS.
Many patients have more than one diagnostic proce-
dure performed (e.g., needle core biopsy, followed by exci-
sion and reexcision of various margins) with DCIS in more
than one specimen. It is not practical to reassemble the foci
of DCIS from two or more specimens to obtain a single
measurement.
For the foregoing reasons, a 1997 consensus report on
the classification of DCIS left the issue of size largely unan-
swered and was unable to address this question.
151
A classifi-
cation system for DCIS that includes lesion size is currently
impractical. Nonetheless, data purportedly describing the
“size” of DCIS are reported. The mean size of 227 lesions
in one series was 2.1 cm, ranging from 1.5 cm in cribriform
to 2.5 cm in comedo DCIS.
269
In a study of cases referred
