Rosen's Breast Pathology, 4e

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Ductal Carcinoma In Situ

diagnosed during 1973 to 1974 in Japan and the United States reported a higher frequency of DCIS in Japanese pa- tients and noted that the carcinomas tended to form bulky, palpable tumors in Japanese women. 75 Pandya et al. 74 com- pared the characteristics of DCIS detected in eras prior to (1969 to 1985) and after the “intensified use of screening” (1986 to 1990) at the Lahey Clinic. The proportion of mam- mographically detected cases increased from 19% to 80%, whereas palpable lesions decreased from 54% to 12%. The proportion of cases presenting with duct discharge and Paget disease also decreased. Comedo DCIS was found in 7% and 38% of palpable and mammographic lesions, respectively. Currently, DCIS is not palpable in the majority of patients with this disease. 76 Negative mammograms may be reported in up to 25% of cases, with a sensitivity ranging from 56% in women younger than 40 years to 67% in the 40- to 49-year age group and 76% in those 50 years or older. 32 Nonpalpable lesions are detected because of imaging findings, Paget dis- ease, nipple discharge, or as an incidental finding in a bi- opsy for a concurrent palpable benign tumor 41,76 (Fig. 11.2). About 25% of biopsy procedures performed for “suspicious” calcifications reveal carcinoma, largely of the intraductal type. 77,78 Duct hyperplasia and sclerosing adenosis (SA) ac- count for the majority of “significant” calcifications that do not prove to be carcinoma. Comedocarcinoma is the type most frequently detected by mammography alone, whereas micropapillary DCIS is more often found as a result of a pal- pable lesion or other clinical signs. 76 Frozen Section Evaluation The diagnosis of DCIS requires histologic sections of ex- cised breast tissue. DCIS can be recognized in frozen sec- tions (FSs), but if any difficulty is encountered, the decision should be immediately deferred to permanent sections be- cause there is a significant risk of trimming away the lesional area if more FSs are made. 79 FS is not appropriate for the diagnosis of mammographically detected, nonpalpable le- sions, unless there are exceptional clinical circumstances. In one study of DCIS, 50% of the lesions were diagnosed at the time of FS, 36% were reported to be benign, 8% were de- ferred, 5% were diagnosed as atypical hyperplasia, and one case was diagnosed as invasive. 80 Approximately 3% of biop- sies reported to be benign at FS prove to contain carcinoma when paraffin sections are examined. 79 Because the sampling of a biopsy is limited during surgery, approximately 20% of patients with a FS diagnosis of DCIS prove to have invasion after multiple paraffin sections of the same biopsy specimen were examined. 81 The use of FS evaluation of margins in breast-conserving surgery has been shown to decrease reoperative rates; how- ever, “technical changes in freezing breast tissue,” specifi- cally those with “high adipose content,” is a major limitation of such analyses besides the obvious difficulty in interpre- tation of “atypical ducts.” 82 The possibility of “skip lesions” of DCIS must be kept in mind when assessing margins of lumpectomies (and nipple margins in nipple-sparing mas- tectomies) by FS analyses. 83

Ultrasound Evaluation Ultrasound is only uncommonly helpful in diagnosing DCIS. In general, “ductal changes” with associated micro- calcifications are the most common sonographic findings in about one-third of the cases of high-grade DCIS, and an irregular hypoechoic mass with an indistinct margin is the most frequent finding in about one-third of non–high-grade DCIS cases. 58 Magnetic Resonance Imaging Magnetic resonance imaging (MRI) has proven to be an ef- fective method for detecting DCIS, especially lesions that lack calcifications. Menell et al. 60 found that MRI was more sensitive than mammography for detecting DCIS overall and for detecting multifocal DCIS. Lesion detection is based on the finding of contrast enhancement in breast parenchyma after injection of a gadolinium contrast agent compared with the preinjection image. 61–63 Orel et al. 64 described three patterns of enhancement associated with DCIS: ductal, re- gional, and a peripherally enhancing mass. The mean size of MRI-detected DCIS was 10 mm. Correlation of immunohis- tochemical studies for vascularity and MRI characteristics of the lesions suggested that tumor angiogenesis contributed to MR enhancement in one series. 61 Contrast-enhanced MRI has proven to be an effective method for the detection of concurrent, unsuspected contralateral carcinoma in women with ipsilateral DCIS. 65 MRI has higher sensitivity for invasive carcinoma (up to 98%) than for DCIS (sensitivity of 60% to 80%). 66 On MRI, DCIS typically has a non-mass, delayed peak enhancement profile; however, this methodology has a high rate of false neg- atives. Gadolinium, the contrast media used in MRI, has been shown to accumulate within the intraductal space of DCIS. 67 Current indications for adjunct MRI include the detec- tion of an occult primary tumor, the examination of dense breast tissue, the presence of known BRCA mutations, and the detection of chest wall involvement. 68 MRI has two main roles in the evaluation of DCIS. The first is assessing the ex- tent of disease, and the other is early detection in breast can- cer screening programs. The sensitivity of MRI for the accurate assessment of DCIS is more than 60%, compared with approximately 55% for mammography and 45% or so for ultrasound 69 ; MRI screening may potentially double the probability of carci- noma detection in a high-risk population compared with either mammography or ultrasound alone. 68,70 Owing to the higher detection rate of otherwise occult significant disease on MRI (including so-called “elsewhere carcinoma”), there is a strong association between preoperative MRI performed in women with DCIS and mastectomy. 71 Palpable DCIS Prior to the widespread use of mammography, palpable tumors were reportedly present in 50% to 65% of women who had DCIS. 72–74 A study comparing breast carcinomas