MBC constitutes less than 1% of all breast cancer cases [1
]. Mucinous or colloid breast cancer is considered to be a rare subtype of breast cancer (invasive ductal breast cancer) and probably slightly more uncommon in men than in women [10
]. Special types such as Paget's disease of the nipple and mucinous breast cancer in a man are extremely rare. To our best knowledge this is the first case reported of mucinous male breast cancer presenting as Paget's disease of the nipple.
We must emphasize that Paget's disease must be differentiated from other skin disorders, such as eczema, and it is usually the presence of an underlying lump that indicates the invasive nature of the lesion. In addition, melanoma and adenoma of the nipple may rarely mimic Paget's disease. The correct diagnosis requires histopathologic interpretation, as clinical signs may be similar.
According to the immunohistochemical analysis the cancer cells were estrogen and progesterone receptor positive. Studies have shown that MBC is more likely to be of high grade at presentation time, affecting mostly elderly males, with retained expression of ER and PR [2
]. In our case reported herein, the patient was 86 years old. In specific, the majority of cancers arising in the male breast are ER positive although this finding does not correlate with a better prognosis, as it occurs in women [14
] Clinical responses to hormonal therapy have been observed in the ER+ patients but not in one ER – patient [16
]. In women, ER expression is usually a marker of differentiation and indicates that the cancer still remains under hormonal influence. This characteristic would also imply that the tumor should be less aggressive and more responsive to hormone therapy. In men, however, ER-positive tumors are associated with higher stage disease [15
]. Postmenopausal women have been found to have tumors that are more likely to be hormone receptor expressers as well and follow a more indolent course [17
]. One possibility is that hormone receptor-positive cancers are a consequence of aberrant steroid receptor up-regulation in the estrogen-starved postmenopausal setting. The tumors over expressing the steroid receptor may have constitutive activation of downstream targets. The fact that most cancers arising in male breasts are ER positive is likely due to the lack of circulating estrogen in the male system, much like in postmenopausal women [2
]. Apart from steroid receptors other immunohistochemical differences between male and female breast cancer must also be considered. For instance, cases of MBC are less likely to overexpress p53 and Erb-B2, which are associated with survival and cell proliferative activity than the female counterparts [2
It appears that MBC has a more aggressive clinical behavior than FBC with a worse outcome when compared stage for stage [18
]. Some studies referred to worse prognosis in men mainly due to anatomic factors (i.e., paucity of breast tissue and close tumor proximity to skin and nipple, facilitating dermal lymphatic spread and early regional and distant metastasis) and delayed diagnosis [13
]. Usually, in MBC symptoms are often delayed and the lag time between first symptoms and surgery in some cases is twice as long as in women [21
]. In the case reported herein, the mammary Paget-like lesion of the skin bearing the nipple was the main symptom. On the other hand, numerous studies have shown that breast carcinoma in males is not biologically more aggressive than in females and the prognosis of patients with breast cancer is the same in male and female patients when disease-specific survival rate, tumour size and axillary involvement are compared [22
Modified radical mastectomy, combined with sentinel-node biopsy by experienced teams, is the standard treatment in case of MBC. Criteria for adjuvant systemic treatment are identical for men and women, although hormonal therapy (tamoxifen) has a more prominent place in the adjuvant setting because of the high percentage of positive hormone receptors in men [25
Owing to its infrequent occurrence, knowledge of the etiology, pathology, immunophenotype and behavior of MBC lags behind that regarding FBC. Numerous studies have confirmed distinct differences in the genetic basis of MBC and FBC [26
]. The poorer prognosis of the male breast carcinoma might be related to ineffective therapies which do not consider these differences in the biological profile of the male tumor. Prognostic and predictive tissutal markers, detected by immunocytochemical methods and useful for therapeutic programming in the female breast cancer have a different significance in the male breast cancer and stress the need for different therapeutic strategies specific for male breast cancer.