A recent study found that there were pathology lab mix-ups in the analysis of prostate biopsy samples in approximately 1 out of 100 prostate biopsies. About 1% of the time, either one patient's biopsy was completely switched with another patient's biopsy; or one patient's biopsy was contaminated with another patient's biopsy material.
Rate of occult specimen provenance complica... [Am J Clin Pathol. 2013] - PubMed - NCBI
COMMENT: this is yet another consideration when deciding whether or not PSA testing is an appropriate screening tool for prostate cancer.