[Laparoscopic renal cyst excision: Large simple renal cyst treatment with renal cell carcinoma cells in its wall. Histogenetic considerations and bibliographic review.]

OBJECTIVE:The incidence of simple renal cysts is very high, especially in elderly people. However, malignant transformation of a simple renal cyst is exceptional. Likewise, the treatment to be carried out, in these rare cases, is controversial, with respect to opting for radical renal surgery. METHODS: We present the case of a patient with a solid nodule in a large cyst. Complete removal of the cyst was performed by transperitoneal laparoscopic technique. The histopathological study of the surgical piece revealed the existence of a cyst with clear renal cell carcinoma with nucleolar grade 2. The clinical evolution has been satisfactory, performing a minimally invasive surgery (laparoscopic cyst excision). DISCUSSION: Although it is considered that surgical treatment of choice is radical surgery in these cases, we believe that nephron sparing surgery may represent a therapeutic option, taking into account the young age of our patient. A histogenetic hypothesis is discussed to explain the appearance of a clear cell tumor in a simple renal cyst. CONCLUSION:The development of a renal cell carcinoma in simple renal cysts is a very infrequent pathology.Laparoscopic total cystectomy is a minimally invasive therapeutic option for the treatment of renal cell carcinoma originating in a simple renal cyst, although it is of an important size. We establish the hypothesis of migration of the cells of the renal collecting tubes into the cyst wall to explain the malignant transformation of the renal simple cyst.