A mastectomy device allows a surgeon to cut skin covering a patient's breast more uniformly. The mastectomy device includes: a vacuum well having a peripheral wall, a closed top and an open bottom which together define a well interior, a valve rotatably mounted to the vacuum well and provided with a through channel, and a cutting tip assembly having a telescoping cutting tip. The cutting tip assembly is connected to the vacuum well such that the cutting tip can be inserted into, and withdrawn from the well interior, via the through channel. Rotation of the valve controls the angular position of the through channel, and thus the orientation of the telescoping cutting tip.