Integrated diagnosis of nevi with severely atypical features and impact of second opinions

A subset of melanocytic proliferations is difficult to classify by dermatopathology alone and their management is challenging.

To explore the value of correlation with dermatoscopy and to evaluate the utility of second opinions by additional pathologists.

For this single center retrospective study we collected 122 lesions that were diagnosed as atypical melanocytic proliferations, we reviewed dermatoscopy and asked two experienced pathologists to reassess the slides independently.

For the binary decision of nevus versus melanoma the diagnostic consensus among external pathologists was only moderate (kappa 0.43; 95% CI 0.25-0.61). If ground truth were defined such that both pathologists had to agree on the diagnosis of melanoma, 13.1% of cases would have been diagnosed as melanoma. If one pathologist were sufficient to call it melanoma 29.5% of cases would have been diagnosed as melanoma. In either case, the presence of dermatoscopic white lines was associated with the diagnosis of melanoma. In lesions with peripheral dots and clods, melanoma was not jointly diagnosed by the two pathologists if the patient was younger than 45 years.

A considerable number of atypical melanocytic proliferations may be diagnosed as melanoma if revised by other pathologists. The presence of white lines on dermatoscopy increases the likelihood of revision towards melanoma. Peripheral clods indicate growth but are not a melanoma clue if patients are younger than 45 years.