Melanoma‐like pigmented cutaneous metastasis of breast carcinoma

Dear Editors,

1.

Cutaneous metastases have been reported in 0.6% to 10.4% of all patients with cancer.1 Breast cancer and melanoma are the most frequent sources of cutaneous metastases.2 Cutaneous metastases of the breast carcinoma may present with a broad spectrum of clinical and histological appearances that lead to diagnostic challenges for dermatologists.2 Because of the potential implications for prognosis and management, the early diagnosis of such lesions is crucial. Pigmented cutaneous metastasis is a rare cutaneous manifestation of an underlying breast malignancy that can be difficult to differentiate from cutaneous melanoma.3, 4, 5, 6, 7 Here, we report a case of metastatic pigmented cutaneous breast carcinoma that mimics malignant melanoma both clinically and dermatoscopically.

A 61‐year‐old woman who had a history of breast carcinoma presented with a black lump on her surgical wound scar. The woman had been diagnosed in 2013 with an infiltrating ductal breast carcinoma for which she underwent breast‐conserving surgery (lumphectomy) and left axillary node dissection. She was then treated with adjuvant chemotherapy consisting of six cycles of cyclophosphamide and adriamycine. She was using 1 mg of oral anastrazole daily for the last 6 years. One year ago, a small itchy pigmented macule had appeared on the border of the incision scar and slowly increased in size. Dermatological examination indicated a black‐brown pigmented ulcerated firm nodule with a diameter of 1 × 1.3 × 1 cm on the incision scar (Figure 1). Dermatoscopy demonstrated a chaotic lesion with sharp borders, which included mostly structureless areas of brown, pink, red, blue‐whitish, and yellow in colour (Figure 2). No pigment network was noticed. Mostly peripheral and asymmetrically distributed small brown globules and serpentine vessels were noted. Fibre sign was also positive. Histopathological examination and immunostaining confirmed the diagnosis of cutaneous metastasis of breast carcinoma.

Figure 1.

Metastatic breast adenocarcinoma presenting as a pigmented ulcerated nodule on the surgical incision scar

Figure 2.

Dermatoscopic examination showed a chaotic lesion with sharp borders and structureless areas of brown, pink, red, blue‐whitish, and yellow in colour. Mostly peripheral and asymmetrically distributed small brown globules and scarce serpentine vessels were recorded. Fibre sign was also positive

Breast carcinoma is the most common cause of cutaneous metastasis in women, which comprises approximately 70% of all cutaneous metastases.8 It metastasises most frequently to the chest and abdominal wall, close to the mastectomy scar. There are different morphological types of cutaneous metastasis of breast carcinoma, including solitary or multiple erythematous infiltrating nodules that might also show a zosteriform pattern, carcinoma erysipeloides, carcinoma encuirasse, carcinoma telangiectaticum, or alopecia neoplastica.2 Pigmented cutaneous metastasis of breast carcinoma is a rare clinical presentation that leads to difficulties differentiating from melanoma not only clinically and dermatoscopically but also histopathologically.3, 4, 5, 6, 7

To our knowledge, there have been very little data on the dermatoscopic findings of skin metastases, and the pigmented forms are one of the rarest. Recently, central hypopigmentation, peripheral pigmented streaks, and small globules and also a bluish hue mimicking a blue‐white veil were reported in the dermatoscopy of pigmented cutaneous metastasis of breast carcinoma.6, 9, 10 Dermatoscopic examination of our patient demonstrated a multi‐component pattern with a blue‐whitish structureless presentation, which is often seen in melanoma. As reported previously, dermatoscopic examination did not help in distinguishing between a diagnosis of pigmented metastatic breast cancer and melanoma in our case as well.

Chernoff et al highlighted that the presence of pigmented metastases, in the absence of a history of melanoma, may suggest a primary breast carcinoma. In addition, we think that the location of the lesion is the most important clinical clue for differential diagnosis because most cutaneous metastases typically occur in anatomical areas close to the primary tumour.

The presence of cutaneous metastasis generally indicates advanced disease and is associated with poor prognosis. Therefore, it is important for dermatologists to recognise a cutaneous metastasis earlier, which can be the first clinical sign of an occult or recurrent malignancy and could significantly impact the patient's overall prognosis. In conclusion, the onset of a new melanoma‐like lesion especially close to the incision scar in patients with a history of malignancy should raise a high index of suspicion for cutaneous metastasis leading to immediate investigations and treatment.