Pathologic sampling of laparoscopically morcellated kidneys: a mathematical model.

Abstract

BACKGROUND AND PURPOSE: Kidney morcellation permits tissue removal through a port site; however, standard methods of histopathologic examination of the numerous specimen fragments thus produced have not been established. We developed a model to guide pathologic evaluation of the morcellated kidney. MATERIALS AND METHODS: A mathematical model was created to determine the quantity of morcellated tissue needed to establish a diagnosis. Inputs into the equation included estimated lesion size, total specimen volume, and the desired certainty of identifying at least a portion of the lesion on pathologic analysis. Nomograms were calculated to illustrate the model and provide clinically relevant guidelines. RESULTS: The hypergeometric distribution was used to develop the formula: P = 1 - (1 - k/N)(n), where k/N represents the fraction of total specimen with tumor, n is the amount of specimen that must be sampled to yield a diagnosis, and P is the probability of encountering the tumor in the sampled tissue. The model provided nomograms that were feasible and would guide a practical approach to the pathologic analysis of laparoscopically morcellated specimens. CONCLUSIONS: The increasing application of laparoscopy to the removal of solid organs with suspected tumors has raised several important issues. Morcellation of these specimens precludes traditional pathologic examination and necessitates an alternative method of specimen sampling and diagnosis. We describe a novel, systematic model to assist in the histopathologic examination of morcellated specimens. Issues of pathologic staging remain unresolved, but this sampling system provides a nonarbitrary framework to help arrive at a histologic diagnosis.