Melanocyte colonization of breast carcinoma by nonneoplastic melanocytes of epidermal origin was first described by Azzopardi and Eusebi in 1977 [
We report on this exceptional clinical and pathological migration phenomenon and demonstrate that histological examination and additional staining are essential to differentiate malignant melanoma from breast cancer melanosis.
A seventy-four-year-old woman, in good condition, was in August 2009 diagnosed with a large tumor of the breast. It was localized in the left upper quadrant with infiltration of the skin and pectoral muscle as well as massive involvement of the axillary lymph nodes. Computerized tomography showed suspicious distant metastases in the mediastinum and lung.
The histological examination after core needle biopsy showed an estrogen receptor positive carcinoma. The patient was initially treated with Letrozole. This treatment induced partial regression of the tumor and metastases. In April 2010 she developed large numbers of heavily pigmented areas on the skin of the affected breast mimicking malignant melanoma, and she was referred to the Department of Plastic Surgery (Figure
(a) Large numbers of pigmented areas on the skin of the affected breast. (b) Pigmented maculae.
A representative excisional biopsy from the pigmented skin was performed, and histological examination showed carcinoma with no evidence of collision tumor.
As her tumor and metastases had exhibited significant regression upon treatment with Letrozole, she was evaluated at a multidisciplinary conference. It was decided to offer the patient mastectomy with axillary dissection and a V-Y plasty using the latissimus dorsi musculocutaneous flap.
The patient was discharged after 8 days of hospitalization in good condition and was referred to The Department of Oncology.
Examination of the mastectomy specimen showed peau d’orange and multiple 1–4 mm heavily pigmented nonelevated areas in the skin (maculae) (Figure
The mammary tissue contained a more than 10 cm large area of indurated tissue, suggestive of carcinoma with signs of lymphangitis carcinomatosis.
Massive vascular tumor embolisation was seen in the entire mammary tissue including the dermis. In several locations, the adenocarcinoma cells had infiltrated the superficial dermal connective tissue and penetrated the dermoepidermal junction (Figure
(a) Melanocytes colonizing the underlying carcinoma cells. (HE × 40). (b) Carcinoma cells surrounded by melan-A-positive melanocytes (×40). (c) Estrogen receptor positive carcinoma cells (×20).
Additional immunohistochemical stainings identified positive estrogen receptor (Figure
The presence of melanin pigmentation is described in various epithelial tumors like carcinomas of the breast, oral mucosa, larynx, salivary gland, prostate gland, and the rectal mucosa [
In the rare cases of visible pigmentation of the skin covering a breast cancer, malignant melanoma should be included in the differential diagnosis. On clinical examination, malignant melanoma most often shows an elevated lesion, whereas the pigmentation of melanosis is at the level of the skin. However, histological examination and additional immunohistochemical staining are essential to differentiate malignant melanoma and breast cancer melanosis.
We hereby confirm that none of the authors of the paper have any conflict of interests what so ever.