Breast papillomatosis

63 year-old woman who consulted due to palpation of a nodule in the junction of the lower quadrants of the right breast. It was a non-painful nodule, without evidence of nipple discharge. Axillary lymph nodes were not palpable.

Bilateral dual-energy contrast-enhancement mammography was performed identifying a fatty breast with several high-density round masses, that have circumscribed margins. They are localised in the lower quadrants of the right breast, with a segmental distribution and a total extension of about 10 cm. No calcifications are identified in the lesions. In the high-energy image, areas of homogeneous enhancement are identified within the masses (Figure 1).

Breast ultrasound showed several grouped complex cystic and solid masses with some areas of ​​nodular morphology that protrudes into the interior of them (Figure 2).

Breast MRI evidenced multiple round masses with circumscribed margins, that are aligned along a ductal system in the lower quadrant of the right breast. These masses are isointense on T1WI and hyperintense on T2WI. In the post-contrast sequences, they present rapid and homogeneous enhancement, with a plateau pattern curve (type 2 curve) (Figure 3). There is a very good correlation between contrast-enhancement mammography and MRI, being these findings highly suggestive of breast papillomatosis.

Using ultrasound-guided control, a core needle biopsy of the largest lesion was performed, being consistent with intraductal papilloma (figure 4).

Papillary neoplasms of the breast encompass a wide range of tumour types ranging from the benign intraductal papilloma [IDP] [as in this case] to in situ and invasive papillary carcinomas [1]. Intraductal papilloma usually forms as a single mural nodule protruding into the lumen. The basic histologic structure consists of a proliferation of the ductal epithelium with myoepithelial cells supported by frond-forming fibrovascular stroma. On ultrasound they are identified as complex cystic and solid masses [2]. The main differential diagnosis for solid cystic masses is: fibrocystic changes, intraductal or intracystic papilloma, cysts with confluent debris, galacoceles, abscesses, hematomas and fat necrosis. [3]. IDP are the most common mases within the milk ducts of the breast and they can arise within the large central ducts usually as a solitary lesion or within the smaller peripheral ducts where they tend to be multiple, being called papillomatosis [4].

It is thought that multiple papillomas confer a greater risk of breast cancer compared to the solitary papilloma of large central ducts. Large papillomas can undergo torsion, infarction and haemorrhage, leading to bloody nipple discharge [1].

Papillary neoplasms occur in women over a wide age range [more frequently 40-50 years of age] and can be shown asymptomatically, by bloody or clear nipple discharge [36%] or as a palpable mass [51%] if they have grown to a large size. Bloody nipple discharge may have higher association with atypical or malignant lesions [5].

Mammography can be normal, or may show solitary or multiple dilated ducts or benign-appearing circumscribed masses. On contrast-enhancement mammography areas of homogeneous enhancement can be identified within the nodules [6]. On US they can be seen as solid nodules or masses that fill ducts with a vascular stalk on colour Doppler. On MRI, they are seen as solid, circumscribed and enhancing lesions that are isointense or slightly hypointense with respect to glandular tissue on T1WI, hyperintense on T2WI but less intense than cysts, and show rapid, homogeneous or heterogeneous enhancement. All three types of curves can appear [persistent, plateau and washout] [7]. Both contrast-enhanced mammography and MRI are very useful for monitoring these lesions and for surgical planning.

Even if the biopsy is negative for malignancy, it is usually resected because there could be areas of atypia or neoplasia that have not been diagnosed in the biopsy, which occur in 8,8-15% of cases and up to 27% in atypical IDP [1, 8, 9]. Intraductal papillomas are classified as lesions of uncertain malignant potential in the breast [B3 lesions]. In 2018 the Second International Consensus Conference on lesions of uncertain malignant potential in the breast [B3 lesions] was published [10]. According to this consensus, a papillary lesion which is visible on imaging should undergo excision with vacuum-assisted biopsy [VAB]. Larger lesions which cannot be completely removed by VAB need open excision. Frequent surveillance must be done [8, 10]. In this case, surgical resection was performed without evidence of atypia in the anatomopathological study.