Introduction and background

Benign breast disease includes a diverse spectrum of proliferative and non-proliferative pathologies, which correspond to different risks for manifestation of clinical breast cancer [1]. One example is the intraductal papilloma (IDP), a benign intraductal proliferation characterized by a fibrovascular core lined by luminal epithelial cells with intervening myoepithelium [2]. Papillomas can be classified into solitary or multiple papillomas [3]. They are subdivided into central papillomas, mostly found in the subareolar region, and peripheral papillomas arising in the terminal duct lobular unit [3]. Previous reports have suggested that the peripheral location is associated with the presence of multiple papillomas, atypia and an increased risk of malignant potential [3, 4]. It is generally recommended that papillary lesions with atypia or malignancy diagnosed on core needle biopsy (CNB) should undergo surgical excision [2, 5,6,7]. Other published data have suggested that surgical excision is also warranted when a benign papillary lesion is diagnosed by CNB [8, 9] as a small but significant percentage ranging from 1 to 4% of benign IDPs upstage to malignancy [2, 5, 10]. Roughly half of these initially benign IDPs have been shown to upstage to malignancy in the tissues adjacent to the previous biopsy site [10]. This presentation serves to describe 2 examples of IDPs which were upstaged to malignancy in peripheral tissues with concordance upon re-review by a radiologist and a pathologist.

Case presentation: imaging/pathologic findings

A 72-year-old woman was found to have suspicious microcalcifications on bilateral screening mammogram (Fig. 1A). Diagnostic mammogram with CC magnification/spot compression was performed (Fig. 1B) demonstrating grouped amorphous calcifications in the posterior right breast at the 7:00 position, 9 cm from the nipple (circled). The number of calcifications in this group had increased compared to the prior mammogram at image A. BIRADS category of 4 was assigned. The patient’s only significant past medical history was hormone replacement therapy since her hysterectomy in the 1980’s until 2 years prior to presentation. She was asymptomatic with no palpable lesions. Stereotactic CNB was performed with pathology that showing fibroadenoma/fibroadenomatoid change with associated microcalcifications adjacent to a small, 1-mm-IDP (Fig. 2). Sonographic evaluation demonstrated appropriate location of the biopsy clip in the biopsy site (Fig. 1D). Ultrasound guidance was utilized for surgical excision with subsequent histologic evaluation positive for cytokeratin AE1/AE3 that demonstrating attenuated staining with e-cadherin consistent with invasive lobular carcinoma (ILC) infiltrating adipose tissue (B). This tissue was distant from the biopsy site and not involving the papilloma. Following re-review by a radiologist and a pathologist, the BIRADS and pathologic-radiology correlation of the significantly upstaged case described above demonstrated concordance.

Fig. 1
figure 1

A 72-year-old woman was found to have suspicious microcalcifications on bilateral screening mammogram (A). Diagnostic mammogram with CC magnification/spot compression at image B demonstrates grouped amorphous calcifications in the posterior right breast at the 7:00 position, 9 cm from the nipple (blue circle). The number of calcifications in this group has increased compared to the prior mammogram at image A (orange circle). BIRADS category of 4 was assigned. Stereotactic core needle biopsy was performed (radiographic imaging of biopsied tissue on image D) with pathology showing IDP with benign features. Sonographic evaluation demonstrated appropriate location of the biopsy clip in the biopsy site (purple arrow, C)

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Fig. 2
figure 2

Core biopsy with a small intraductal papilloma, H&E stain, 100× magnification (A). Cytokeratin AE1/AE3 Immunostain highlights invasive lobular carcinoma infiltrating adipose tissue, 100× magnification (B)

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A 65-year-old female presented with clear nipple discharge from a single duct in the left breast. Sonographic evaluation demonstrated debris within one of these ducts at the 6:00 position of the retroareolar left breast. Subsequent biopsy was scheduled but no intraductal mass was identified via ultrasound at that time. On a 3-month follow-up, a hypoechoic lesion in the left retroareolar region at the 5:00 to 6:00 position was identified (Fig. 3A, blue arrow), and BIRADS 4 was assigned. Ultrasound-guided automated tissue excision and collection (ATEC) vacuum assisted core biopsy yielded IDP with benign features. Image B shows radiograph of the excised specimen. Figure 4 demonstrates photomicrograph fragments of a sclerosing intraductal papilloma with no overt atypical features (A). Excisional biopsy demonstrated residual intraductal papilloma (B). Cribriform ductal carcinoma in situ (DCIS), low nuclear grade was identified in the breast tissue adjacent to, but not involving the papilloma, spanning 10 mm in longest dimension (C).

Fig. 3
figure 3

65-year-old female with clear nipple discharge, sonographic evaluation showing hypoechoic lesion in the left retroareolar region at the 5:00 to 6:00 (A, blue arrow), BIRADS 4 was assigned. Ultrasound-guided ATEC vacuum assisted core biopsy yielded IDP with benign features. Image B shows radiograph of the excised specimen

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Fig. 4
figure 4

Photomicrograph shows fragments of a sclerosing intraductal papilloma, hematoxylin and eosin, total magnification 20× (A). Excisional biopsy demonstrated residual intraductal papilloma, total magnification 20× (B). Cribriform ductal carcinoma in situ, low nuclear grade was identified in the breast tissue adjacent to, but not involving the papilloma, spanning 10 mm (C)

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Conclusion

Given the low upstaging rate of IDP lesions identified as benign on CNB to excisable malignant lesions such as DCIS and ILC, close surveillance rather than surgical excision of IDPs without atypical features on CNB may be considered. This management strategy would spare patients the emotional and painful toll of potentially unnecessary procedures. However, it is notable that perhaps as many as half of malignant upgrades occur in the tissues adjacent to the intraductal papilloma, as occurred in the patients described above. This trend underscores the risk of under-sampling and how perhaps more generous sampling of the adjacent tissue about the target lesion should be considered. Among the explored clinical, radiologic and pathologic features of IDPs at our institution, multiplicity was the only factor that significantly correlated with pathologic upstaging within the benign core biopsy group.