MUCI positive cutaneous metastasis with transepidermal elimination from a breast carcinoma
In February 2010, a 48-year-old Argentine woman had undergone tumorectomy in her left breast with diagnosis of an invasive ductal carcinoma with low nuclear and histological differentiation grades; estrogen (ER) and progesterone (PR) receptors were negative and Her2/neu was positive. In September 2011, a mastectomy with immediate breast reconstruction was performed due to local tumor recurrence and the patient received systemic chemotherapy. In March 2012, she consulted because multiple skin nodules had appeared 3 months before. Lung, bone, and hepatic metastases were also detected.\nPhysical examination revealed an erythematous nodule that was 4 cm in diameter, polylobulated, and with ulcerated surface on the chest region. Multiple erythematous painful nodules from 5 mm to 2 cm were distributed on her chest and over the reconstructed breast ().\nA skin biopsy of one of the small lesions revealed skin metastasis from breast carcinoma (ER-PR-Her2/neu+). Histopathologically, tumor cell nests were seen in the dermis. By immunohistochemistry, MUCI expression was studied and a strong reaction was found with a mixed pattern at the plasma membrane and in the cytoplasm (). Some epidermal cells at the Malpighi stratum also showed cytoplasmic positive staining. Tumor cells in the papillary dermis appeared to penetrate through the epidermis, suggesting transepidermal elimination. The epidermis showed no signals of ulceration (), and in some malignant cells, a MUCI moderate reaction was found.