Primary sweat gland carcinosarcoma of the scrotal skin

Background: Carcinosarcoma is a biphasic tumor composed of malignant epithelial and mesenchymal elements. Although the tumors have been reported in different locations, they rarely occur in the skin and have not been reported in the skin of external genitalia. Case report: We present such a case in a 71-year-old Taiwanese man. He had had a long-term indolent nodule on scrotal skin, but it enlarged rapidly in 2 weeks. Wide excision of the tumor was performed. Results and Discussion: The pathologic examination revealed a sweat gland carcinosarcoma consisting of admixed mucin-producing adenocarcinoma and solid spindle cell sarcoma. The two components exhibited contrasting immunohistochemical profiles with the epithelial component diffusely positive for epithelial markers and S-100 protein, while the sarcomatous component positive for vimentin and smooth muscle actin but negative for epithelial markers and S-100 protein. The immunoreactivity for S-100 protein in the epithelial component supports sweat gland origin. The tumor behaved aggressively. Local recurrence and distant metastases to lungs and brain occurred 6 months and 18 months later. The patient died of the disease 20 months after the initial diagnosis.