This part of Urology covers two inter-linked issues: Firstly, the study of pathologies and diseases that are located or potentially located in a single part of the organ, thus leaving the rest of it healthy and disease free; secondly, the study of surgical peculiarities in the targeted removal of part of the organ leaving the rest intact and functioning, known as segmentectomy. The value of the relationship between these two groups of study is clear if one wants to consider the pathological, clinical, and therapeutic aspects of each field.

This pathology will explain why pathologic phenomena or processes occur, and in some cases only temporarily, and remain in the specific part of the organ in which they started.

Clinical results will demonstrate if and when it is necessary to treat the disease or pathological processes in order to alleviate the issues or prevent them from getting worse. Therapeutic indications, in our case surgical, are part of the clinical discipline.

The surgical, segmentary treatment of the kidney consists of removing one or more renal lobes according to the manifestation and extent of the disease. Since the surgical technique begins by identifying the calyx in which the pathologic lobe opens, the lobectomy technique used is also called a calicectomy.

It is well known that it is possible to remove the affected part of the kidney through surgical procedures other than those specified above. This occurs in the case of small or medium-size tumors that are circumscribed and have no infiltration of the surrounding parenchyma. In this instance we are speaking of partial renal resection.

It is thus timely to establish the difference between the two kinds of procedures, both considered to be “nephron sparing.” The difference lies in both the surgical technique and in the obtainable results. The surgical anatomy of segmentectomy is based on calyces, from which the name “calycectomy” is derived (Figs. 1.1 and 1.2). The calyx heads the segment or lobe that is to be removed; in order to reach the calyx one needs to enter the renal sinus and, using the major calyx as a guide, find the desired minor calyx. The calyx amputation and the traction on it favors the segmental parenchymal delimitation that unloads in it and the consequent ablation.

While segmentectomy starts with intrarenal access (Figs. 1.3 and 1.4), partial nephrectomy starts from outside of the kidney, where the parenchymal incision is made just around the lesion that is to be removed, independent of whether the lesion is cortical, medullary, or calyceal (Figs. 1.5 and 1.6).