Abstract

We present two cases of metastatic skin carcinomas, both resulting from mammary carcinomas. Tumor cells in the dermis had not contained mucin, whereas mucin had depositted in the stroma around the tumor nests. In case 1, tumor cells including mucin in the cytoplasms had sporadically indurated into the epidermis. These results consisted with those previously reported on extramammary Paget's disease. It is suggested that proliferation and differentiation of tumor cells in the epidermis is inhibitted. The lesions in the metastasis in the scalp showed mucin deposition around the degenerated hair follicle. Mucin is known to cause a degeneration of the external root sheath cells, as seen in alopecia mucinosa. The findings of previous reports and of our study suggest that mucin derived from mammary carcinoma may be the cause of hair loss in alopecia neoplastica.