Breast cancer is the most commonly diagnosed cancer among women. Positive margin status after breast-conserving surgery (BCS) is a predictor of higher rates of local recurrence. Intraoperative margin detection helps to complete tumor excision at the first operation. A margin tool that is capable of imaging all six margins of large lumpectomy specimens with both high resolution and fast speed (within 20 min) is yet to be developed. Deep UV light allows simultaneous excitation of multiple fluorophores and generating surface fluorescence images. We have developed a deep UV fluorescence scanning microscope (DUV-FSM) for slide-free, high-resolution and rapid examination of tumor specimens during BCS. The DUV-FSM uses a deep UV LED for oblique back illumination of freshly excised breast tissues stained with propidium iodide and Eosin Y and motorized XY stages for mosaic scanning. Fluorescence images are captured by a color CCD camera. Both invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC) images showed excellent contrast from that of the normal cells in color, tissue texture, and cell density and shapes. This contrast have been consistently observed in all samples (n = 20) we have imaged so far. Statistical analysis showed a significant difference (p<0.0001) in nucleus-to-cytoplasm (NC) ratio between normal and invasive tissues. Thus, it may be utilized either visually by a trained individual or quantitatively by an algorithm to detect positive margins of lumpectomy specimens intraoperatively.