European Urology

We read this article [1] with special interest. The authors have very convincingly clarified the issues related to atypical urine cytology samples, for which the dilemma persists as how to follow up such cases. The authors concluded that when used as a reflex test to arbitrate atypical urine cytology, a negative ImmunoCyt result can be used to avoid cystoscopy in patients with a history of low-grade cancer or without a history of urothelial cancer.

Urinary cytology has low sensitivity (5%) for detecting low-grade tumors, so the chances of a false-negative result are very high in such tumors with cytology alone, whereas immunocytology has high sensitivity and specificity for both low- and high-grade tumors [2]. The authors [1] have applied immunocytology in patients with atypical cytology samples only. We are of opinion that immunocytology may be used as a second-level reflex test in negative cases of cytology as well to avoid the high false-negative results associated with it; otherwise, such cases will remain unevaluated.

The authors [1] have not discussed the limitations of the ImmunoCyt test. A positive test means the presence of one confirmed red or green positive cell. If fewer than five positive cells are counted, the manufacturer of the ImmunoCyt kit [3] (used in this article) recommends evaluating a second sample. This issue has not been discussed by the authors [1].

A study by Vriesema and colleagues [4] of the diagnostic efficiency and reproducibility of the positive ImmunoCyt/uCyt test found high interobserver variability, so it is important to repeat the test as recommended by the manufacturer before declaring a test to be positive. Vriesema and co-authors concluded that the validity of ImmunoCyt was insufficient to justify the omission of cystoscopy in patients for follow-up for superficial urothelial cancer. This issue needs to be clarified further before using immunocytology as a second-level reflex test.

Conflicts of interest

The authors have nothing to disclose.