Track

Abstract

PReferentially expressed Antigen in MElanoma (PRAME) immunohistochemistry is an ancillary tool currently used in facilitating the distinction between benign and malignant melanocytic proliferations, particularly in diagnostically challenging cases. In situ and invasive melanomas often exhibit a diffuse nuclear immunoreactivity for PRAME, in contrast to the infrequent and usually non-diffuse staining observed in nevi. Although PRAME expression has been characterized as a relatively specific marker of melanoma, diffuse PRAME expression has been reported in a variety of benign melanocytic nevus subtypes. Anecdotally, this investigative team has encountered diffuse PRAME expression in benign melanocytic proliferations with oncocytic metaplasia in clinical practice. Oncocytic metaplasia refers to the development of an appearance similar to cells in certain glandular tissues, characterized by abundant granular and eosinophilic cytoplasm due to the proliferation of mitochondria. These cytologic changes can be encountered in both conventional melanocytic nevi and malignant melanoma. To the authors’ knowledge, PRAME expression has not been examined in melanocytic nevi with oncocytic metaplasia in current literature. This retrospective study aims to determine if PRAME is consistently expressed in melanocytic nevi with oncocytic change. Recognizing that PRAME can be positive in benign melanocytic nevi can help guard against the pitfall of overcalling these lesions as being of borderline or malignant potential.