Kidney morcellation in laparoscopic nephrectomy for tumor - Recommendations for specimen sampling and pathologic tumor staging

Laparoscopic nephrectomy is a novel approach for small renal tumors in sele cted patients; however, removal of the kidney through the small laparoscopi c abdominal wall incision site requires the kidney to be morcellated into s mall fragments while still in situ. Morcellation presents two problems for the pathologist. First, guidelines for optimal sampling of morcellated frag ments have not been described. Second, morcellation precludes complete pTNM tumor staging, in particular, tumor size, margins, and renal vein involvem ent. Based on our initial experience with 23 laparoscopic nephrectomies/nep hroureterectomies (13 clinically suspected neoplasms, confirmed pathologica lly as renal cell carcinoma [RCC, n = 7], urothelial carcinoma of the renal pelvis [n = 3], angiomyolipoma [n = 1], and cystic nephroma [n = 1], and 1 0 clinically benign entities) and a conservative statistical model, we pres ent a decision analysis model of various specimen sampling protocols that o ptimize cost, labor, or time to diagnosis (single vs sequential sampling). Using the tumor-to-kidney volume ratio (TKR), calculated from preoperative radiologic imaging and specimen gross weight, several specimen sampling alg orithms were compared. For the average situation in which TKR is greater th an or equal to0.15, the algorithm that most significantly optimizes cost an d labor is one that initially samples 5% of the morcellated specimen. Howev er, additional sampling may be required in one fourth of the cases. The opt imal amount of sampled tissue may indeed be less than 5% because this assum es no suspicious tissue is grossly visible and in all our cases of RCC gros sly visible tumor was identified. Additional nomograms for a spectrum of TK R, sampling success, and cost are presented to allow pathologists their own discretion in determining optimal sampling of the morcellated kidney. Tumo r staging is severely limited by morcellation. Tumor size, renal capsule in volvement, and renal vein involvement cannot be fully pathologically evalua ted for RCC, whereas invasion cannot be definitively assessed for urothelia l carcinoma of the renal pelvis. Knowledge of the radiologic features (lesi on size, capsule, and vein involvement) is important in sampling and stagin g morcellated kidneys removed laparoscopically.