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LOINC Code 74861-6: Chromosome 17 copy number/nucleus FISH (Tiss) [Entitic number]

74861-6 is a LOINC code used to identify Chromosome 17 copy number/nucleus FISH (Tiss) [Entitic number] in laboratory and clinical observation data. You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges. LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Chromosome 17 copy number/nucleus. It is commonly used with the system or sample type Tiss.

Reviewed by HealthAssure Clinical TeamUpdated 21 May 2026

What is this code?

LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component Chromosome 17 copy number/nucleus. It is commonly used with the system or sample type Tiss.

When is it used?

  • Used in lab systems, EHRs, and clinical data exchange.
  • May identify a test, observation, survey item, or clinical document request rather than a diagnosis.
  • Status: ACTIVE
  • Order vs observation: Observation
  • Method: FISH

What it does not mean

  • The code identifies the observation or test, not the actual result.

Key facts

Chromosome 17 copy number/nucleus in Tissue by FISH
Chromosome 17 copy number/nucleus
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 [LOINC49683-6]. 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.
CEP17; Chr 17 copy num; Chromosom; Chromosome 17 centromere; Chromosome Enumeration Probe 17; Chromosomes; Entitic; Entitic number; Fluorescent in situ hybridization; Genetics; Heredity; Heritable; Inherited; Molecular pathology; MOLPATH; No; Num; Point in time; QNT; Quan; Quant; Quantitative; Random; Tissue; Tissue, unspecified

Where you may see this code

You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges.

Common synonyms

Chromosome 17 copy number/nucleus FISH (Tiss) [Entitic number]Chromosome 17 copy number/nucleus in Tissue by FISHChr 17 copy num/nucleus EntNum Tiss FISHChromosome 17 copy number/nucleusMOLPATHChromosome 17 copy number/nucleus, TissueEntNum

Frequently asked questions

Code details

Code74861-6
SystemLOINC
Display nameChromosome 17 copy number/nucleus FISH (Tiss) [Entitic number]
DescriptionChromosome 17 copy number/nucleus
Short nameChr 17 copy num/nucleus EntNum Tiss FISH
ComponentChromosome 17 copy number/nucleus
PropertyEntNum
TimingPt
System (specimen)Tiss
ScaleQn
MethodFISH
ClassMOLPATH
Example units#
StatusACTIVE
Order/ObservationObservation

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released2.48
Last changed2.73

Consumer names

Chromosome 17 copy number/nucleus, Tissue

Part names

Chromosome 17 copy number/nucleusEntNumPtTissQnFISHEntitic numberPoint in time (spot)Tissue and SmearsFluorescent in situ hybridization (FISH)

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from LOINC. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.