Whose tumor is this? FISHing for the answer

: Errors in tissue handling and accessioning during procurement as well as in the laboratory occasionally occur; rarely these errors may result in specimen misidentification and therefore misdiagnosis. Tissue "pick-ups" or "floaters" are difficult to avoid in large, busy histology laboratories. While misidentification problems can usually be sorted out based on clinical history, they are occasionally problematic. We report two misidentified cases that presented to the Gastrointestinal Pathology Division at the Johns Hopkins Hospital and a novel method that was used to correctly solve the problem.