Benign and primary malignant breast tumors are quite common, but melanoma involvement of breast is only seen in 1.3%-2.7% of all malignant mammary tumors[8]. Melanoma is the most rapidly increasing cancer and 20% of patients diagnosed with melanoma will develop metastasis via hematologic or lymphatic routes[9]. Sometimes it can present many years after the primary diagnosis[10]. Breast metastases may be asymptomatic and/or palpable as well-defined nodules. On mammography, breast metastases showed clear nodular shadows without calcification or structural deformation. Therefore, clinical history, cytology and histology are very important for diagnosis.
According to our experience and literature report[10], cytoplasmic melanin pigment allowed a highly suggestive of breast metastases, therefore histological examination was not required. It should be emphasized that melanin must exist in malignant cells because hemosiderin simulates melanin in macrophages to a certain extent. The pigmented epidermotropic form of breast carcinoma can also mimic a melanoma[11]. However, although characteristic, the pigment is often not visible in cytological samples. Metastatic melanoma can also simulate a variety of cellular and architecture phenotypes, including primary breast malignancies[12]. Thus, a panel of biomarkers played a vital role in establishing the melanocytes originate of tumor cells. Immunohistochemistry for S100, HMB45, or Melan-A help to confirm the diagnosis.
Cutaneous melanoma is one of the tumors with a high frequency of dissemination to the breast.The prognosis for a patient with a newly diagnosed cutaneous melanoma depends mainly on the thickness of the primary tumour and the presence or absence of metastasis[13]. Due to the poor prognosis of patients with metastatic melanoma, active surgical treatment should be avoided. With regard to chemotherapy, ipilimumab, vemurafenib, interferon alfa-2b, dacarbazine and interleukin-2 have low response rates and are associated with serious adverse events[14]. Due to the low radio-sensitivity of melanoma cells, radiation therapy plays a limited role in the control of the natural history of metastatic melanoma[15]. However, the treatment of metastatic melanoma has been modified by the introduction of targeted therapy and immunotherapy.Treatments by using selected BRAF inhibitors combined with mitogen-activated protein kinase inhibitors have significantly improved response and overall survival[16]. Antibodies that block immune checkpoint proteins, including CTLA4, PD-1, and PD-L1 are FDA approved for treating melanoma[17]. While these therapies have limitations, identifying biomarkers to improve patient selection and discovering future therapeutic targets will hopefully lead to further treatment advances.