Methodology: IHC

Clinical Significance:
Identifies: The gp100 protein, found in premelanosomes.  As such, HMB-45 is a highly sensitive and specific marker of melanoma, particularly in the metastatic setting.  The epitope targeted by HMB-45 behaves as an ‘oncofetal’ antigen that is not expressed in normal, resting melanocytes but is present in reactive and neoplastic melanocytic processes. Furthermore, as a marker of a premelanosomal protein, it is also an excellent marker of clear cell sarcoma as well as PEComas. Subcellular Localization: Cytoplasmic, granular

Organ: Skin & Mucosa

Disease State: Large Cell Undifferentiated Malignant Neoplams

CPT Code(s): 88342 or 88341. The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

Turnaround Time: Within 1-2 business days of receipt

Schedule: Monday - Friday

Specimen Requirements:
• Formalin-fixed, paraffin-embedded (FFPE) tissue block or cell block - OR - • 1 unstained slide for each test requested plus 3-4 additional unstained slides cut at 4µm