Diagnosis by cytologic means is what the mathematicians would describe as elegant; the methods are often simple but richly nuanced, while the results can be profound though succinctly stated. Tiny samples atraumatically obtained are at the heart of both the elegance and the dif? culties of this subspecialty. Following initial successes of traditional exfoliative cytology, further applications were long constrained by the fact that few body surfaces present themselves for direct collection of exfo- ated cells. Thus, it was inevitable that advances in nonoperative evaluations for speci? c body...