Reliability of the histopathologic diagnosis of malignant melanoma in childhood.

OBJECTIVE To assess interrater reliability in the diagnosis of malignant melanoma in children. DESIGN, SETTING, AND PARTICIPANTS We collected 85 slides of melanomas diagnosed in patients younger than 17 years through a network of dermatopathologists and dermatologists. The slides were classified into 3 categories: (1) slides from children with metastatic melanoma; (2) slides from disease-free children with a follow-up of less than 5 years; (3) slides from disease-free children with a follow-up of 5 years or longer. Category 1 was considered the gold standard. Four pairs of expert dermatopathologists reviewed the slides and classified them into melanoma, nevus (including Spitz nevus), or ambiguous tumors. INTERVENTION None. MAIN OUTCOME MEASURE Concordance between pairs of experts. RESULTS For category 1 slides (n = 20), the concordance was weak to moderate. For category 2 slides (n = 47), the concordance was weak. For category 3 slides (n = 18), the concordance was poor to moderate. CONCLUSION This study demonstrates that the reliability of diagnosis of melanoma in childhood is poor, even when submitted to experts.