Apocrine carcinoma of the male breast: a case report of an exceptional tumor

Apocrine carcinoma of the male breast is an exceptional malignant tumor. It does not have a particular clinical or radiological appearance, but it's microscopically characterized by the presence of granular cells and foamy cells representing over 90% of tumor cells. These cells express most of the time the GCDFP-15 and the androgen receptors. This tumor is a distinct molecular entity. In this observation, we report the case of a 70 year old man presenting apocrine carcinoma of the left breast diagnosed at the stage of lung metastasis.


Introduction
Apocrine carcinoma of the breast is a malignant tumor, microscopically characterized by the presence of granular cells and foamy cells representing over 90% of tumor cells. It does not have a particular clinical or radiological appearance, but it's a distinct molecular entity. We report an exceptional observation of apocrine carcinoma of breast in a man.

Patient and observation
He's a 70 years old man who had for 9 years ago a painless nodule at the left breast. It was movable relative to superficial and deep plans. Then, this nodule presented a rapid augmentation of its volume with adhesion to both superficial and deep plans, and inflammatory opposite signs. Mammography showed an ACR5 lesion measuring 4 cm long axis. We realized a fine-needle aspiration cytology, a spread on slides and stained with May-Grünwald Giemsa (MGG) which showed isolated carcinomatous cells, sometimes forming three-dimensional clusters. Their nucleus is large and irregular with nucleolus. The cytoplasm is abundant. We did not observe myoepithelial cells and the background is necrotic and hemorrhagic (Figure 1). A biopsy of the tumor was performed. It

Discussion
Apocrine carcinoma of the breast is a rare malignant tumor whose incidence varies between 0.3% and 4% of all female's breast cancer [1]. This tumor is exceptional in men. Indeed, only a dozen cases have been described in the literature [2]. Like our patient, the average age of onset is between the sixth and seventh decade [1].
Its clinical mammographic and sonographic characteristics mimic those of non-apocrine breast invasive carcinoma. The cytology after fine needle aspiration may have a role in orienting. As in our patient, it shows apocrine cells with cell and nuclear atypias, a large irregular nucleus and a prominent nucleolus with abundant cytoplasm [3]. Macroscopically, apocrine carcinoma is in the form of a nodule or endo-cystic growths, often multicentric [1].
Histologically, the tumor is defined as a carcinoma showing in more than 90% of tumor cells, cytological features of apocrine cells Although apocrine carcinoma is a distinct histological entity, however, there is no sensitive and specific immunohistochemical marker for confirming apocrine differentiation.
Immunohistochemical study shows an expression of GCDFP-15 in 76% to 100% of cases. The GCDFP-15 is a glycoprotein originally isolated from breast cyst fluid. It's localized in cytoplasmic vesicles, and in osmiophilic granules. With the development of this marker, a more objective diagnostic criterion has been introduced [4].
Androgen receptors are expressed in 54% of cases [5]. Moreover, tumor cells can express B72.3, estrogenic-beta receptors, HER2, p53 and Ki-67 [1]. Usually, these tumors do not express the estrogen receptor-alpha, progesterone receptors and bcl-2. [1] Concerning the molecular study, we note the presence of However, studies involving the use of anti-androgens are in progress [6]. The survival rate at 5 years was significantly better for the apocrine carcinoma (72%) with a longer time to recurrence compared to non-apocrine carcinoma. Prognostic factors are essentially the mitotic account and TNM stage. [1] Conclusion Apocrine carcinoma of the breast is a distinct histological and molecular entity. It is rare in women and exceptional in man.
Studies are being conducted to use anti-androgens such as targeted therapy.

Competing interests
Authors declare no competing interests.

Authors' contributions
Authors contributed to the diagnosis of this tumor, revising critically the article for important intellectual content; and final approval of the version to be published.