Impact of second opinion pathology review in the diagnosis and management of atypical melanocytic lesions: A prospective study of the Italian Melanoma Intergroup (IMI) and EORTC Melanoma Group

Background: The clinical value of an expert pathological review in patients with an atypical melanocytic lesion diagnosis remains unclear. Herein, we evaluate its impact in a prospective clinical study.

Methods: Patients with newly diagnosed or suspected atypical melanocytic proliferations and challenging skin tumours were reviewed prospectively by a specialised dermatopathologist through the nationwide 'Second Opinion Platform' of the Italian Melanoma Intergroup (IMI) network. The primary aim was the rate of major discrepancies that impacted patient management. Major discrepancies in diagnosis between referral and specialised review were blindly re-analysed by a panel of European Organisation for Research and Treatment (EORTC) Melanoma pathologists.

Results: The samples submitted to central review included 254 lesions from 230 patients. The most frequent referral diagnoses were atypical melanocytic nevi of different subtypes (74/254, 29.2%), invasive melanomas (61/254, 24.0%), atypical melanocytic proliferations (37/254, 14.6%), AST (21/254, 8.3%) and in situ melanomas (17/254, 6.7%). There was disagreement between referral diagnosis and expert review in 90/254 cases (35.4%). Most importantly, 60/90 (66.7%) were major discordances with a change to the patient's clinical management. Among the 90 discordant cases, the most frequent new diagnosis occurred in World Health Organisation (WHO) Pathway I, followed by WHO Pathway IV (64/90 and 12/90, respectively). In total, 51/60 cases with major discrepancies were blindly re-evaluated by EORTC Melanoma pathologists with a final interobserver agreement in 90% of cases.

Conclusion: The study highlights that a second opinion for atypical melanocytic lesions affects clinical management in a minor, but still significant, proportion of cases. A central expert review supports pathologists and clinicians to limit the risk of both over- and under-treatment.