Fluorescent in situ hybridization (FISH) is a steadfast, economical technique that is capable of detecting the abnormality in minimal amounts of tumor cells on formalin-fixed, paraffin-embedded (FFPE) tissue sections. 1p/19q codeletion is a constructive prognostic marker for oligodendroglial tumors .The test compares result in tumors with simple deletions of 1p or 19q to those with relative deletions defined as the presence of both increased copy number (polysomy) and 1p/19q codeletion.