This article, authored by Arthur C. Allen and Sophie Spitz, provides a detailed clinicopathological analysis of the criteria for diagnosing and prognosing malignant melanoma. The authors clarify the histological diagnosis of nevi, juvenile melanomas, and malignant melanomas, emphasizing the importance of distinguishing between benign and malignant lesions. They outline the histogenetic concepts that underlie the relationship between junctional nevi, intradermal nevi, juvenile melanomas, and melanocarcinomas. The study is based on a comprehensive analysis of 934 cases, divided into three series: 337 patients with primary melanocarcinomas, 623 patients with metastatic melanomas, and 311 patients with indeterminate cases. The authors discuss the clinical and histological features of various types of nevi, including intradermal, junctional, compound, juvenile, and malignant blue nevi. They highlight the challenges in distinguishing benign juvenile melanomas from adult malignant melanomas, especially in postpubertal individuals. The article also explores the histological estimation of the age of nevi and the factors influencing the transformation of junctional nevi into melanocarcinomas. The authors conclude by emphasizing the importance of dermal invasion as a key criterion for diagnosing superficial melanocarcinomas.This article, authored by Arthur C. Allen and Sophie Spitz, provides a detailed clinicopathological analysis of the criteria for diagnosing and prognosing malignant melanoma. The authors clarify the histological diagnosis of nevi, juvenile melanomas, and malignant melanomas, emphasizing the importance of distinguishing between benign and malignant lesions. They outline the histogenetic concepts that underlie the relationship between junctional nevi, intradermal nevi, juvenile melanomas, and melanocarcinomas. The study is based on a comprehensive analysis of 934 cases, divided into three series: 337 patients with primary melanocarcinomas, 623 patients with metastatic melanomas, and 311 patients with indeterminate cases. The authors discuss the clinical and histological features of various types of nevi, including intradermal, junctional, compound, juvenile, and malignant blue nevi. They highlight the challenges in distinguishing benign juvenile melanomas from adult malignant melanomas, especially in postpubertal individuals. The article also explores the histological estimation of the age of nevi and the factors influencing the transformation of junctional nevi into melanocarcinomas. The authors conclude by emphasizing the importance of dermal invasion as a key criterion for diagnosing superficial melanocarcinomas.