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Published on: August 18, 2023
Immunohistochemistry utilization in the diagnosis of melanoma
Matthew S Dinehart1, Scott M Dinehart2, Suporn Sukpraprut-Braaten3
1Department of Pathology, University of Vermont, Burlington, Vermont.
Insights
Immunohistochemical (IHC) stains are frequently used in melanoma diagnosis, despite guidelines suggesting H&E stains suffice. This study found higher IHC utilization than expected, indicating a gap between current practice and Medicare coverage policies for melanoma diagnosis.
Area of Science:
- Dermatopathology
- Oncology
- Medical Diagnostics
Background:
- Immunohistochemical (IHC) stains are common in dermatopathology.
- Utilization trends for IHC in melanoma diagnosis are not well-documented.
- Current Medicare Local Coverage Determinations (LCDs) permit H&E staining alone for most pigmented lesions, including melanoma.
Purpose of the Study:
- To investigate the utilization trends of immunohistochemical (IHC) stains in the diagnosis of melanoma.
- To compare current IHC usage in melanoma diagnosis with existing Medicare LCDs.
Main Methods:
- Retrospective analysis of histopathology reports for biopsy-proven melanomas.
- Data abstracted included laboratory, dermatopathologist, IHC use, stain types, invasion depth, and melanoma subtype.
- Chi-squared test was used to evaluate associations between characteristics and IHC utilization.
Main Results:
- 356 melanomas were analyzed; IHC was used in 64% of diagnoses.
- IHC was used in 58.8% of invasive melanoma cases and 70.7% of melanoma in situ (MIS) cases.
- IHC utilization exceeded expectations based on current guidelines.
Conclusions:
- Melanoma diagnosis shows higher immunohistochemical (IHC) stain usage than previously reported.
- Current Medicare LCDs for melanoma diagnosis do not align with observed clinical practice.
- Further research is needed to establish appropriate-use criteria for melanoma IHC.
Background:
The use of immunohistochemical (IHC) stains in dermatopathology is commonplace; however, little is known regarding utilization trends in melanoma diagnosis. Current Medicare local coverage determinations (LCDs) state that most pigmented lesions, including melanoma, can be diagnosed using H&E alone.
Methods:
Histopathology reports for all biopsy-proven melanomas excised between January 1, 2017 and June 30, 2018, at a single dermatology clinic, were identified with the following parameters abstracted: laboratory/dermatopathologist rendering the diagnosis, whether IHC was performed, type/number of stains utilized, presence/depth of invasion, and melanoma subtype. The association of characteristics with IHC utilization was evaluated using χ2 test for categorical variables.
Results:
Three hundred and fifty six eligible melanomas were identified. IHC was employed in 228 (64%) of the diagnoses. Invasive melanoma was diagnosed in 199 cases (55.9%) while 157 (44.1%) were identified as melanoma in situ (MIS). Of the 228 that utilized IHC, 117 were performed on invasive melanoma (58.8%) and 111 were performed on MIS (70.7%).
Conclusion:
Our findings suggest a higher IHC usage for the diagnosis of melanoma than previously reported. Existing LCDs regarding IHC utilization in melanoma do not reflect the current state of practice. Further investigation regarding IHC utilization and the development of appropriate-use criteria for melanoma IHC is necessary.
