Nipple Adenoma (NA), also known as erosive adenomatosis or florid papillomatosis of the nipple, is a benign proliferation of the lactiferous ducts of the nipple[7, 9]. It was first described as a distinct clinicopathological entity in 1955 by Jones et al[10]. NAs typically present in women in the fourth and fifth decades of life, exceptionally they have also been reported in men or children, and they generally occur unilaterally. The initial clinical presentation is a hard-elastic nodule that distorts the nipple profile, usually causing swelling, inflammation, erythema, or erosion with serous or haematic discharge, possibly associated with pain in the nipple-areolar region[1]. Our patient showed a single tender palpable tumor, increasing the left nipple dimension. The World Health Organization (WHO) classification of breast tumors established in 2012[9], defined nipple adenomas as a compact proliferation of small tubules lined by layers of epithelial and myoepithelial cells, with or without proliferation of the epithelial component, around the collecting ducts of the nipple[11]. Although NA represents a rare benign neoplasm, the main issue is the differential diagnosis with nipple Paget's disease, DCIS of low-grade, syringomatous adenoma, and subareolar solitary central papilloma[2, 3].
This rare entity can include various histological patterns. The main histological feature is the ductal proliferation of glandlike structures within the stroma of the nipple, with well-circumscribed margins without encapsulation[7, 11–13]. Confirmation of the presence of at least two distinct layers of myoepithelial cells in neoplastic ducts seems to be the most important finding for the differential diagnosis of ductal carcinoma. Immunohistochemical staining using CD10, p63, alfa-smooth muscle actin, calponin, or desmin can be useful for myoepithelial cell detection in neoplastic ducts. An adequate histological and immunophenotypic analysis is recommended for discriminating the pseudo-invasive pattern from breast cancer precursors and aggressive carcinoma[11, 14, 15].
Despite its benign behavior, the expanding growth pattern and frequent local recurrence could harm patients' quality of life, especially for women of childbearing age who need to maintain intact the function of the nipples.
Association with malignant breast carcinoma has been previously described; with regards to the probability of a tumor developing from NA, no reliable data are available so far[16, 17].
The optimal management of benign nipple lesions during pregnancy is controversial and scarce evidence has been produced. On one side non-urgent surgical procedures are generally avoided during pregnancy, to minimize the risks of anesthesia and surgical complications that can negatively affect the mother and the fetus. On the other side, nipple lesions can represent a major impairment in the physiological process of lactation and breastfeeding, if not promptly treated. Thus, management of benign disorders of the breast during pregnancy is usually conservative and surgery is mandatory only in case of rapid enlarging or discordance in the triple assessment, but it could also be considered for symptomatic lesions or to reduce the risk of future breastfeeding impairment[8]. Although the total excision of the nipple-areola complex with associated underlying wedge resection of the breast parenchyma or complete resection of the nipple is reported in the literature, these procedures could be considered overly aggressive for benign lesions[18, 19]. Since NA represents a completely benign lesion, we recommend considering local surgical excision as the appropriate first-choice treatment. In this case, we performed a curative resection without nipple complete excision. Moreover, the presence of an abnormal mass of the nipple could have affected the sucking reflex during breastfeeding. Breast surgical techniques that preserve the column of subareolar parenchyma appear to have a greater potential for successful breastfeeding, in our case surgical enucleation of NA with preservation of some of the lactiferous ducts has granted successful lactation even on the affected breast.
Regularly scheduled follow-up is recommended in these patients, regardless of the therapeutic methods, since NA's risk of recurrence or progressing into a malignancy can not be fully excluded.
In conclusion, we reported a rare case of NA limited local excision in a pregnant young female. Traditional complete removal of the nipple may result in overtreatment and unsatisfactory aesthetic outcome. Conservative local treatment can be considered after the end of the first trimester of pregnancy and can allow the functional preservation of the nipple in young women.