Pathologists' agreement on treatment suggestions for melanocytic skin lesions

Abstract

Background: Although treatment guidelines exist for melanoma in situ and invasive melanoma, guidelines for other melanocytic skin lesions do not exist.

Objective: To examine pathologists' treatment suggestions for a broad spectrum of melanocytic skin lesions and compare them with existing guidelines.

Methods: Pathologists (N = 187) completed a survey and then provided diagnoses and treatment suggestions for 240 melanocytic skin lesions. Physician characteristics associated with treatment suggestions were evaluated with multivariable modeling.

Results: Treatment suggestions were concordant with National Comprehensive Cancer Network guidelines for the majority of cases interpreted as melanoma in situ (73%) and invasive melanoma (86%). Greater variability of treatment suggestions was seen for other lesion types without existing treatment guidelines. Characteristics associated with provision of treatment suggestions discordant with National Comprehensive Cancer Network guidelines were low caseloads (invasive melanoma), lack of fellowship training or board certification (melanoma in situ), and more than 10 years of experience (invasive melanoma and melanoma in situ).

Limitations: Pathologists could not perform immunohistochemical staining or other diagnostic tests; only 1 glass side was provided per biopsy case.

Conclusions: Pathologists' treatment suggestions vary significantly for melanocytic lesions, with lower variability for lesion types with national guidelines. Results suggest the need for standardization of treatment guidelines for all melanocytic lesion types.

Keywords: invasive melanoma; melanocytic skin lesions; melanoma in situ; pathology; skin biopsies; treatment guidelines.

Figure 1:

Pathologist treatment suggestions for cases diagnosed as dysplastic nevi and Spitz tumors. N’s represent total interpretations.

Figure 2:. Two Examples of Melanoma In Situ Glass Slide Biopsies evoking High and Low Variability in Treatment Suggestions by the Study Participants.

Both cases were diagnosed as melanoma in situ by consensus panel and 17 out of 18 pathologists. For Case A, 29% of participating pathologists suggested a lower treatment (<0.5cm) and 18% suggested a higher treatment (≥ 1cm margin) than NCCN guidelines, showing relatively large variability in treatment suggestions. Case A is relatively small (~4mm) and does not have an obviously atypical melanocytic proliferation at low magnification. Higher magnification allows the identification of a poorly circumscribed intraepidermal melanocytic proliferation. In contrast, Case B had a smaller proportion of pathologists (12%) rendering a treatment suggestion lower than NCCN guidelines, and no pathologists suggested a higher treatment than NCCN guidelines. Case B is a larger lesion (~8mm) that more readily is identifiable as an atypical lentiginous and nested proliferation with pagetoid scatter.