Dermatology Online Journal

Cutaneous metastasis of breast carcinoma mimicking malignant melanoma in scalp
Nuria Martí¹, Inmaculada Molina¹, Carlos Monteagudo², Verónica López¹, Laura García¹, Esperanza Jordá¹
Dermatology Online Journal 14 (11): 12

1. Department of Dermatology, Hospital Clinico Universitario, Valencia, Spain. nuriamarfa@hotmail.com
2. Department of Pathology, Hospital Clinico Universitario, Valencia, Spain.

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Abstract

Cutaneous metastases of carcinoma of the breast may present a broad spectrum of clinical and histologic appearances. Pigmented metastases of a breast carcinoma have rarely been described in the literature and these metastases are usually located on the chest and abdominal wall close to the mastectomy scar. We report an unusual case of a cutaneous metastasis of carcinoma of the breast simulating malignant melanoma.

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Figure 1
Figure 1. Black nodule on the occipital side of the scalp

A 51-year-old woman was diagnosed in September 2002 with an infiltrating ductal breast carcinoma and pulmonary metastasis. Three months before a 0.7 x 0.9 cm black nodule with irregular borders had appeared on the occipital side of her scalp (Fig. 1). The histological study of the pigmented nodule showed clusters of atypical epithelial cells containing melanin in granules in the cytoplasm, mainly located at the dermoepidermal junction and in the upper dermis (Fig. 2A: hematoxylin/eosin x40).

Figure 2a	Figure 2b
Figures 2a & 2b. Clusters of atypical epithelial cells containing melanin in granules in the cytoplasm, mainly located in the upper dermis and at the dermoepidermal junction. There were malignant cells arranged in cords and islands simulating nevus cell nests. (H/E A: x40, H/E B: x400)

There were malignant cells arranged in cords and islands simulating nevus cell nests (Fig. 2B: hematoxylin/eosin x400). The immunohistochemical study showed positive staining for Cytokeratins:AE-1/AE-3 (Fig. 3A x400), EMA, and strogen receptor (Fig. 3B x400) in the tumor cells. Moreover, melanocytes were also found in the tumor nests and they were positive staining for HMB-45 (Fig. 4A x400) and Melan-A (Fig. 4B x400). With the final diagnosis of pigmented metastasis of a breast carcinoma, fluorouracil, cyclophosphamide, and epirrubicine were administrated. After that, the patient underwent a modified radical mastectomy and radiotherapy.

Figure 3a	Figure 3b
Figures 3a & 3b. The immunohistochemical study showed positive staining for Cytokeratins: AE-1/AE-3 and estrogen receptor in the tumor cells.

Figure 4a	Figure 4b
Figure 4a & 4b. Moreover, melanocytes were also found in the tumor nests and they stained positively for HMB-45 and Melan-A.

Carcinoma of the breast is the most common source of cutaneous metastases in women and these metastases are usually located on the chest and abdominal wall close to the mastectomy scar [1, 2]. Epidermotropic metastases from a visceral carcinoma are a rare phemomenon, most commonly observed in breast carcinoma [3]. Exceptionally, pigmented metastases of a breast carcinoma have been described and are usually located in the scalp.

As an explanation for the presence of melanin pigments in metastatic carcinoma cells, Masson [4] postulated that there was phagocytosis of melanin pigments by the carcinoma cells from the epidermis. Azzopardi and Eusebi [5] described in their review of the related literature that melanin pigment is frequent in breast carcinoma with epidermotropism, but selective staining for melanin is usually needed to detect the pigmentation. Kohki Konomi et al. [6] obtained evidence for the presence of a chemotactic factor that attracts melanocytes, present in the supernatant of a metastatic tumor culture.

The clinical and histological differentiation of pagetoid malignant melanoma and epidermotropic pigmented metastases of breast carcinoma may be very difficult when pigmented cells are found within the carcinoma. The arrangement of the tumor cells and the presence of mucin favors the diagnosis of carcinoma. Immunohistochemical studies are useful to corroborate the diagnosis.

In our case, there was an accumulation of melanin, mainly in the cytoplasm of the atypical epithelial cells of the metastasis; colonization of melanocytes was found within the metastasic lesion. Another exceptional feature of this pigmented metastasis was its distant location from the primary tumor and its hematogenous origin, in contrast to the usual lymphatic spread.

References

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