A peroperative probe for guiding a manual excision tool. The probe includes a detection head, an optical fiber for the reception and guidance of a signal emitted by radioactive tracers and fluorescent molecules in a tissue area, a photo-detector for converting the emitted signal into an electrical signal, a transmitter for transmitting information carried by the electrical signal to an analysis equipment, and a fastener for attaching the probe onto the manual excision tool, so that the excision tool can be used to remove a portion of tissue from the tissue area emitting the signal.