Minimal or no residual prostatic adenocarcinoma on radical prostatectomy: A 5-year experience with vanishing carcinoma phenomenon'

Context.-"Vanishing carcinoma phenomenon" (VC) has been defined as the finding of minute or no cancer on radical prostatectomy specimens after a positive biopsy. Objective.-To discuss our experience with VC and to recommend guidelines for its detection. Design.-One thousand seven hundred forty-one radical prostatectomy specimens (2004-2009) processed by whole-mount section procedure yielded 21 (1.2%) cases with VC and 6 (0.34%) cases with minimal carcinoma (≤ 2 mm) in the radical prostatectomy specimen. To find the eluding carcinoma in VC cases or more carcinoma in minimal carcinoma cases, the following was done: 3 levels of all the paraffin blocks were obtained; if negative, the paraffin blocks were melted, the tissue was flipped, and 3 levels were prepared. The tumor bank frozen tissue was also processed for routine examination. Results.-Three deeper levels in the radical prostatectomy specimen of 21 VC cases failed to show malignancy; however, the flipping and recutting of the tissue yielded a focus of carcinoma (1-5 mm) in 16 of 21 cases and in 3 of 16 cases in the saved frozen tissue. In 1 of the 6 cases with minimal carcinoma, subsequent recuts of the flipped tissue displayed carcinoma (2 foci of tumor,<1 mm each). Conclusions.-In VC we recommend: embed and process any remaining prostatic tissue including any saved fresh-frozen tissue; obtain 3 levels of each paraffin block; if results are negative, melt and flip the tissue and obtain 3 more levels. Following the above guidelines, a hidden carcinoma may be detected in the majority of the cases of VC.