ABSTRACT
Chromogenic in-situ hybridization [CISH] is a molecular cytogenetic technique that utilizes non-fluorescent molecules as reporters for the detection of molecular alterations. The clinical experience with CISH is limited. The present study aimed to evaluate the possibility of utilization of CISH in routine pathology laboratory setting. A total of 177 different tumors and 10 different control tissues collected from three different laboratories were tested. Two tumor cell lines were used for validation studies. Both commercial and in-house CISH probes were utilized for in-situ hybridization. CISH correlated strongly with the more established fluorescent in-situ hybridization technique. Tissue fixation and processing was crucial for the efficiency of CISH hybridization. There was marked variation in the efficiency of hybridization of different tissue types, most prominent in the time required for tissue pre-treatment. Also there was variation in the efficiency of hybridization of the same tissue type from different sources. CISH is a useful alternative for detection of molecular genetic abnormalities in routinely fixed tissue. However, tissue fixation and processing is crucial for success of in-situ hybridization experiments and implementing a uniformly utilized fixation and processing protocols is essential