LOINC display name : Chromosome 17 copy number/nucleus FISH (Tiss) [Entitic number];
LOINC long common name : Chromosome 17 copy number/nucleus in Tissue by FISH;
LOINC short name : Chr 17 copy num/nucleus EntNum Tiss FISH;
LOINC description : The average number of Chromosome 17 fluorescent signals in nuclei are determined in
order to calculate the average ratio of HER2 to Chromosome 17 copy number [LOINC:
49683-6]. This term is based on, but not limited in use to, the PathVysion HER-2 DNA
Probe Kit, which detects amplification of the ERBB2 gene (HER2 locus) via fluorescence
in situ hybridization (FISH) in formalin-fixed, paraffin-embedded human breast and
gastric cancer tissue specimens. The kit contains two probes: one specific to the
HER-2/neu gene locus (ERBB2 gene, 17q11.2-q12) and another targeting the alpha satellite
DNA sequence at the centromeric region of chromosome 17 (17p11.1-q11.1), called CEP17
(Chromosome Enumeration Probe 17). The average number of HER2 signals [LOINC: 74860-8]
along with CEP17 signals are determined by microscopic examination within the same
set of nuclei. The specimen is positive for ERBB2 gene applification if the mean ratio
of HER2 to CEP17 signals per nucleus is greater than or equal to 2.00.;