Test Catalog

Test ID: HMB45    
HMB45 Immunostain, Technical Component Only

Useful For Suggests clinical disorders or settings where the test may be helpful

Aids in the identification of activated and neoplastic melanocytes

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

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).

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

The HMB45 immunostain identifies an antigen that is associated with a premelanosomal glycoprotein found in activated and neoplastic melanocytes. Most melanomas (approximately 90%) react with HMB45. HMB45 staining is cytoplasmic and is usually diffuse, but may be focal. Benign nevi (moles), and other tumors that have melanin production (such as peripheral nerve sheath tumors), also stain positively.

Interpretation Provides information to assist in interpretation of the test results

This test includes only technical performance of the stain (no pathologist interpretation is performed). Mayo Clinic cannot provide an interpretation of tech only stains outside the context of a pathology consultation. If an interpretation is needed, refer to PATHC / Pathology Consultation for a full diagnostic evaluation or second opinion of the case. All material associated with the case is required. Additional specific stains may be requested as part of the pathology consultation, and will be performed as necessary at the discretion of the Mayo pathologist.


The positive and negative controls are verified as showing appropriate immunoreactivity and documentation is retained at Mayo Clinic Rochester. If a control tissue is not included on the slide, a scanned image of the relevant quality control tissue is available upon request. Contact 855-516-8404.


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 Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

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 fresh.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Kapur RP, Bigler SA, Skelly M, Gown AM: Anti-melanoma monoclonal antibody HMB45 identifies on oncofetal glycoconjugate associated with immature melanomsomes. Journal of Histochemistry and Cytochemistry 1992;40(2):207-212

2. Orchard, GE: Comparison of immunohistochemical labeling of melanocyte differentiation antibodies melan-A, tyrosinase and HMB-45 with NKIC3 and S100 protein in the evaluation of benign naevi and malignant melanoma. The Histochemical Journal 2000;32(8):475-481

3. Wick MR, Swanson PE, Rocamora A: Recognition of malignant melanoma by monoclonal antibody HMB-45. An immunohistochemical study of 200 paraffin-embedded cutaneous tumors. Journal of Cutaneous Pathology 1988;15(4):201-207

4. Yu CH, Chen HH, Liu CM, et al: HMB-45 may be more sensitive marker than S-100 or melan-A for immunohistochemical diagnosis of primary oral and nasal mucosal melanomas. J Oral Pathol Med 2005;34(9):540-545