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HelpTest Code GPNMB Glycoprotein Non-Metastatic Melanoma Protein B (GPNMB), Technical Component Only
Ordering Guidance
This test includes only technical performance of the stain (no pathologist interpretation is performed). If diagnostic consultation by a pathologist is required order PATHC / Pathology Consultation.
Shipping Instructions
Attach the green "Attention Pathology" address label (T498) and the pink Immunostain Technical Only label included in the kit to the outside of the transport container.
Specimen Required
Specimen Type: Tissue
Supplies: Immunostain Technical Only Envelope (T693)
Container/Tube: Immunostain Technical Only Envelope
Submit:
Formalin-fixed, paraffin-embedded tissue block
OR
2 Unstained, positively charged glass slides (25- x 75- x 1-mm) per test ordered; sections 4-microns thick
Secondary ID
623081Useful For
Screening kidney tumors for genetic alterations
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| IHTOI | IHC Initial, Tech Only | No | No |
| IHTOA | IHC Additional, Tech Only | No | No |
Testing Algorithm
For the initial technical component only immunohistochemical (IHC) stain performed, the appropriate bill-only test ID will be reflexed and charged (IHTOI). For each additional technical component only IHC stain performed, an additional bill-only test ID will be reflexed and charged (IHTOA).
Method Name
Immunohistochemistry (IHC)
Reporting Name
GPNMB IHC, Tech OnlySpecimen Type
TECHONLYSpecimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| TECHONLY | Ambient (preferred) | |
| Refrigerated | ||
Reject Due To
| Wet/frozen tissue Cytology smears Nonformalin fixed tissue Nonparaffin embedded tissue Noncharged slides ProbeOn slides Snowcoat slides |
Reject |
Clinical Information
Glycoprotein non-metastatic melanoma protein B (GPNMB) is a transmembrane glycoprotein expressed in numerous cancer types. In kidney cancers, GPNMB can be used as a marker for tumors containing the genetic alterations of TSC1, TSC2, MTOR and TFE3/TFEB. Tumors containing these alterations consist of angiomyolipoma, renal cell carcinomas with alterations of TFE3/TFEB genes, renal cell carcinomas with TSC1, TSC2, MTOR alterations, and TFE3-rearranged mesenchymal tumors. Recent studies suggest that some TFE3-rearranged ossifying fibromyxoid tumors may lack GPNMB expression.
Interpretation
This test does not include pathologist interpretation, only technical performance of the stain. If interpretation is required, order PATHC / Pathology Consultation for a full diagnostic evaluation or second opinion of the case.
The positive and negative controls are verified as showing appropriate immunoreactivity.
Interpretation of this test should be performed in the context of the patient's clinical history and other diagnostic tests by a qualified pathologist.
Cautions
Age of a cut paraffin section can affect immunoreactivity. Stability thresholds vary widely among published literature and are antigen dependent. Best practice is for paraffin sections to be cut within 6 weeks.
The charge of glass slides can be affected by environmental factors and subsequently may alter slide staining. Sending unsuitable glass slides can result in inconsistent staining due to poor slide surface chemistry.
Best practices for storage of positively charged slides:
-Minimize time slides are stored after being unpackaged
-Limit exposure to high humidity and heat
-Minimize exposure to plastic
Clinical Reference
1. Tekin B, Folpe AL, Dasari S, et al. TFE3-rearranged ossifying fibromyxoid tumors are uniquely negative for glycoprotein non-metastatic melanoma protein B: A study of 13 TFE3-rearranged mesenchymal tumors. Hum Pathol. 2025;157:105768
2. Alesi N, Asrani K, Lotan TL, Henske EP. The Spectrum of Renal "TFEopathies": Flipping the mTOR Switch in Renal Tumorigenesis. Physiology (Bethesda). 2024;39(6):347-359
3. Li H, Argani P, Halper-Stromberg E, et al. Positive GPNMB immunostaining differentiates renal cell carcinoma with fibromyomatous stroma associated with TSC1/2/MTOR alterations from others. Am J Surg Pathol. 2023;47(11):1267-1273
4. Salles DC, Asrani K, Woo J, et al. GPNMB expression identifies TSC1/2/mTOR-associated and MiT family translocation-driven renal neoplasms. J Pathol. 2022;257(2):158-171
Method Description
Immunohistochemistry on sections of paraffin-embedded tissue.(Unpublished Mayo method)
Day(s) Performed
Monday through Friday
Report Available
1 to 3 daysSpecimen Retention Time
Until staining is completedPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
88342-TC, primary
88341-TC, if additional IHC
LOINC Code Information
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 623082 | GPNMB IHC, Tech Only | No LOINC Needed |