We report a case involving a 65-year-old woman with skin invasion and destruction by left large breast cancer(T4cN0M0, Stage ⅢB). She had severe anemia with recurrent bleeding on the cancer surface and needed blood transfusion, and massive malodorous effusion from the skin lesion resulted in hypoalbuminemia and recurrent bacteremia. Metronidazole gel treatment for malodorous effusion and postmenopausal hormonal therapy were administered at first. After using Mohs' paste 4 times with 1- or 2-week intervals, the bleeding and effusion stopped, and the primary cancer tumor almost disappeared. Bacteremia also improved with antibiotics, and amelioration of distress was observed. Following this, systemic chemotherapy was performed. Mohs' paste was a very useful method for symptom management of malignant skin lesions with bleeding and massive effusion.