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HMB-45 staining in benign and malignant melanocytic lesions. A reflection of cellular activation
H G Skelton1, K J Smith, T L Barrett
1Department of Dermatopathology, Armed Forces Institute of Pathology, Washington, DC 20306-6000.
Abstract:
The antibody HMB-45 used as an immunohistochemical reagent has often been labeled as a marker for melanoma, even though some benign lesions have been noted to show positive staining reactions with this reagent. Biopsy specimens from 225 benign and malignant melanocytic lesions were examined after immunoperoxidase staining for S-100 protein and HMB-45. The lesions studied included common acquired nevi, spindle cell and epithelioid cell nevi (Spitz nevi), cellular blue nevi, deep penetrating nevi, congenital nevi, nevi from hormonally reactive areas (genital), malignant melanoma, and desmoplastic malignant melanoma. A positive reaction for HMB-45 was seen in the dermal component in a high percentage of each of these types of lesions except for the common acquired nevi and the desmoplastic malignant melanomas that were uniformly negative for HMB-45 in the dermal component. HMB-45 correlates with melanosome production and thus a melanocytic origin of HMB-45-positive cells. HMB-45 may correlate best with factors that stimulate melanocytic proliferation and production of melanosomes.
Insights
The HMB-45 antibody, a melanoma marker, also stains benign melanocytic lesions. Its reactivity correlates with melanosome production, indicating melanocytic origin and proliferation in various nevi and melanomas.
Area of Science:
- Dermatopathology
- Immunohistochemistry
- Oncology
Background:
- The HMB-45 antibody is commonly used as an immunohistochemical marker for melanoma.
- However, positive HMB-45 staining has been observed in some benign melanocytic lesions, questioning its specificity.
Purpose of the Study:
- To evaluate the expression of HMB-45 in a wide spectrum of benign and malignant melanocytic lesions.
- To determine the correlation of HMB-45 staining with melanosome production and melanocytic proliferation.
Main Methods:
- Immunoperoxidase staining for S-100 protein and HMB-45 was performed on 225 biopsy specimens.
- Lesions included various types of nevi (common acquired, Spitz, cellular blue, deep penetrating, congenital, genital) and melanomas (malignant, desmoplastic malignant).
Main Results:
- HMB-45 showed positive staining in the dermal component of most benign and malignant melanocytic lesions studied.
- Common acquired nevi and desmoplastic malignant melanomas were uniformly negative for HMB-45 in the dermal component.
- HMB-45 reactivity was found to correlate with melanosome production, suggesting melanocytic origin.
Conclusions:
- HMB-45 is a useful marker for melanocytic differentiation, correlating with melanosome production.
- Its expression is influenced by factors stimulating melanocytic proliferation, and it is present in various melanocytic lesions beyond just melanoma.