Pathology review of thin melanoma and melanoma in situ in a multidisciplinary melanoma clinic: impact on treatment decisions

Abstract

Purpose: Patients with thin melanoma (<or= 1.0 mm) and melanoma in situ (MIS) represent the majority of newly diagnosed melanoma. We estimated the impact of expert review of outside pathology material on the staging and thus treatment decisions affecting patients referred to a multidisciplinary clinic with early-stage melanoma.

Patients and methods: We studied patients with a diagnosis of thin melanoma or MIS referred to H. Lee Moffitt Cancer Center from 2006 to 2009. After comparing the referring laboratory and in-house dermatopathologic interpretations, we calculated any differences in diagnosis and tumor staging and the potential impact of differences in diagnosis and staging on prognosis and surgical treatment using the National Comprehensive Cancer Network clinical guidelines.

Results: The overall pathologic discordance rate in diagnosis was 4% (15 of 420 patients; 95% CI, 2% to 6%). The overall change in tumor staging rate was 24% (97 of 405 patients; 95% CI, 20% to 28%). Pathology review led to changes in surgical excision margins in 12% of patients (52 of 420 patients; 95% CI, 9% to 16%) and in the decision about whether to perform a sentinel lymph node biopsy in 16% of patients (67 of 420 patients; 95% CI, 13% to 20%). Key pathologic factors, particularly mitotic rate, were frequently missing from outside pathology reports.

Conclusion: Our data suggest that review of thin melanoma or MIS by an expert dermatopathologist results in frequent, clinically meaningful alterations in diagnosis, staging, prognosis, and surgical treatment. Referral of these patients to a multidisciplinary melanoma clinic is appropriate, and management of such patients should include review of the biopsy whenever feasible.