Gastric/Gastroesophageal (GE) Junction HER2/Neu Immunohistochemistry with Reflex to FISH

CPT Code(s):

  • 88360 FISH reflex
  • 88368 x 2

Methodology:

Immunohistochemistry

Performed:

Weekly

Reported:

Immunohistochemistry is reported within 7 days. If Gastric HER2/Neu FISH is requested, the report will be provided within 9 days.

Use:

This test is used to determine eligibility for anti-HER2/Neu therapies in gastric and gastroesophageal (GE) junction tumors.

Specimen Requirements:

A paraffin block containing the representative gastric/GE junction tumor or at least 5 unstained slides

Unacceptable Conditions: Frozen

Stability: Indefinite

Collection Procedure:

-

Reference Values:

In Notes below

Interpretation Data:

Surgical Specimens (Resections): A score of 0 is no reactivity or membranous reactivity (staining) in or = 10% of invasive tumor cells.

Biopsy Specimens: A score of 0 is no reactivity or no membranous reactivity (staining) in less than 5 clustered tumor cells. A score of 1+ is tumor cell clusters (greater than or equal to 5 cells) with a faint/barely perceptible membranous reactivity (staining) regardless of percentage of invasive tumor cells stained. A score of 2+ is tumor cell clusters (greater than or equal to 5 cells) with a weak-to-moderate complete, basolateral or lateral membranous reactivity (staining) regardless of percentage of invasive tumor cells stained. A score of 3+ is tumor cell clusters (greater than or equal to 5 cells) with a strong complete, basolateral or lateral membranous reactivity (staining) regardless of percentage of invasive tumor cells stained.

Notes:

HER2
Interpretation
Staining
Intensity
Score
Surgical
Resections
Biopsies
Negative 0 No reactivity or
membranous
reactivity in
< 10% of tumor
cells
No reactivity or
membranous
reactivity in < 5
clustered tumor
cells
Negative*
(*reflex FISH)
1+ (40x) Faint/barely
perceptible
membranous
reactivity in
> 10% of tumor
cells; cells are
reactive only in
part of their
membrane
Tumor cell cluster
(> 5 cells) with a
faint/barely perceptible
membranous
reactivity irrespective
of percentage
of tumor cells
stained.
Equivocal*
(*reflex FISH)
2+ (10 - 20x) Weak-to-moderate
complete,
basolateral or
lateral
membranous
reactivity in
> 10% of tumor
cells
Tumor cell clusters
(> 5 cells) with a
weak to moderate
complete, basolateral
or lateral
membranous reactivity
irrespective
or
percentage of tumor
cells stained.
Positive 3+ (2.5 – 5x) Strong
complete,
basolateral or
lateral
membranous
reactivity in
> 10% of tumor
cells
Tumor cell clusters
(> 5 cells) with a
strong complete,
basolateral or lateral
membranous reactivity
irrespective of
percentage of tumor
cells stained.

References:

  • Hofmann M, Stoss O, Shi D, Buttner R, van de Vijver M, Kim W, et al. Assessment of a HER2 scoring system for gastric cancer: results from a validation study. Histopath 2008; 52:797-805.
  • Ruschoff J. HER2 diagnostics in gastric cancer-guideline validation and development of standardized immunohistochemical testing. Virch Arch 2010; 457:299

UFHPL Test #: 90025

Reported Notes:

-

Result:

-