392
Chapter 11
MARGINS OF EXCISION
Microscopic examination of histologic sections is necessary
to determine whether DCIS is present at the margin of a
surgical biopsy specimen. Macroscopic examination of the
gross specimen is unreliable for this purpose, and the use
of FSs, while possible, is impractical in most laboratories.
82
A transected duct containing DCIS that is present at a
margin identified by ink applied to the gross specimen or
some other standardized marking procedure is reported as
a “positive” margin.
326
DCIS involving lobular glands (can-
cerization of lobules) is considered to be a risk factor of lo-
cal recurrence and should be reported as a positive margin
if present at the margin of the specimen.
327
In cases with a
positive margin, the report should indicate the extent of in-
volvement with terms such as
focal
(limited to one or two
microscopic fields) or
more than focal.
When the margin is
not directly involved, the closest approach of DCIS to the
margin should be stated with a measurement in millimeters.
The term
close
has been variably defined, but the most fre-
quent usage is for carcinoma within 1 mm of the margin.
Margins of a lumpectomy can be assessed by taking ei-
ther radial (perpendicular) or shave sections. Shave sections
are assessed by obtaining samples of the surface of the post-
excision biopsy cavity. Any DCIS found microscopically in
this tissue is considered to be indicative of a positive mar-
gin.
151
Radial (perpendicular) sections offer the considerable
advantage of determination of extent (width) of clearance.
A novel combination radial–shave method of margin as-
sessment has been described, but this is a cumbersome and
impractical method.
328
The sampling of secondary (biopsy
cavity shave) margins has become a popular technique for
the assessment of margins.
329
These secondary margins, of-
ten all six margins (as of a cube) are taken separately by the
surgeon. The technique has been found to decrease the need
for reexcision after lumpectomies by one-half.
330
An aggressive approach to initial resection(s), that is,
large resection volume, may avoid positive margins and
lower the risk of recurrence or the need for additional sur-
gery. At the present time, the need of radiation therapy is de-
termined by whether or not the margin clearance for DCIS is
wide enough. Thus, the apparently opposing goals of nega-
tive margins and acceptable cosmetic results have to be bal-
anced. One of the most important determinants of adequate
excision may be “excision volume” that may be objectively
assessed as the specimen to carcinoma (S:C) ratio.
331,332
The attainment of negative margins in some cases of
DCIS proves to be a Sisyphean task. Significant risk factors
for persistently positive margins, encountered in approxi-
mately one-quarter to one-third of cases, include multifocal-
ity and nodal positivity. In such cases, the use of multiple
reexcision biopsies to attain negative margins, often in mul-
tiple procedures, is considered to be a “safe” alternative to
mastectomy.
333
Occasionally, it may be difficult to determine whether
proliferating ductal epithelial cells at a cauterized surgical
margin represents a hyperplastic or neoplastic process. In
this setting, immunostaining with high molecular weight cy-
tokeratins (CK5/6 and K903) may be helpful since ADH and
cases, the lymph node was positive only on IHC. No addi-
tional nodal metastases were found in two patients who had
a subsequent axillary dissection. Two (9.6%) of 21 women
with microinvasive ductal carcinoma had a positive SLN,
one of which was detected only by IHC. An additional posi-
tive lymph node was found in the full axillary dissection in
the patient with an H&E-positive SLN.
A positive SLN was found in 4 (10%) of 39 patients
with DCIS and in 1 (7%) of 14 patients with microinvasive
ductal carcinoma studied by Sakr et al.
321
The SLNs were
involved by ITC or micrometastases. Leidenius et al.
322
found that 5 (7%) of 74 patients with DCIS had a positive
SLN, including 3 women with ITC. DCIS with a positive
SLN were significantly larger (median, 50 mm; range, 45
to 60 mm) than DCIS with negative SLN (median, 18 mm;
range, 1 to 110 mm). However, only one of the five patients
with a positive SLN had a palpable lesion. The architecture
of the DCIS with positive SLN was as follows: cribriform
(
n
:2), cribriform and comedo (
n
:1), comedo (
n
:1), and
micropapillary (
n
:1).
The results of SLN biopsy in patients who had DCIS
diagnosed by needle core biopsy were reported by Huo
et al.
323
SLNs were obtained from 103 patients among
whom 4 (4%) had one positive lymph node. Three of these
patients had invasive carcinoma in their excisional biopsy
specimens and metastatic foci in the SLN measuring 0.5 to
6 mm. The fourth patient with DCIS had only ITC in
one SLN.
Several conclusions can be drawn from the foregoing
studies of SLN mapping in patients with DCIS:
• The frequency of finding a positive SLN in a patient
with pure DCIS is 10% or less. Metastatic foci in these
cases are likely to be micrometastases or ITC. The risk
of having a positive SLN is greater for high-grade, mass-
forming, and larger lesions.
• DCIS with microinvasion (T1
mic
) generally has a risk
as high as 15% for SLN metastasis, but the frequency in
some studies overlaps with the risk in pure DCIS.
• Additional lymph node metastases are rarely found in
a completion axillary dissection, with a slightly greater
frequency when there is microinvasion.
• If SLN biopsy is being considered as part of the pri-
mary surgical management of a patient with DCIS di-
agnosed in a needle core biopsy specimen, the yield
will be higher if the procedure had been performed
on patients who were most likely to have invasive car-
cinoma in the lumpectomy specimen. Risk factors for
this “upgraded” diagnosis include the following: high-
grade DCIS, necrosis, lobular extension, a palpable
or radiographic mass at the site of DCIS, and larger
lesion size (median 2.5 vs. 1.5 cm) based on imaging
studies.
Disseminated tumor cells have been found in the bone
marrow patients with in DCIS. The yield was in 13% (34/266)
of patients in one series,
324
and in 21.1% (4/19) in another.
325
The clinical significance of such findings in DCIS, as in inva-
sive carcinoma, is uncertain at this time.
