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Chapter 11

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.

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