Three-dimensional (3D) histology provides a complete 3D representation of the margins of a tumor specimen on histological slides. This eliminates diagnostic gaps and provides maximum sensitivity in identifying tumor outgrowths. The method is used to confirm tumor-free margins or, in case of an incomplete tumor resection, to make even very small infiltrated areas visible with topographic orientation. The basic principle of 3D histology is the conversion from the 3D structure of the tumor-specimen margins into a two-dimensional view of histological sections. The 3D margins are flattened with their outside down and then cut into pieces, suitable for histopathological procedures of cryo or paraffin sections. The management of a full 3D histology needs a tight communication between the surgeon and the pathologist. Clear and safe rules are necessary to enable both the surgeon and the pathologist to point out areas of incomplete tumor excisions very precisely. Using a circle as representation of the separation between tumor base and margin, the pathologist can point out the exact position of an outgrowth by referring to different positions on the circle in clock times. This system will be sufficient to point out tumor outgrowths. The advantage is that it is very simple to communicate and easy implemented in any electronic communication.