Track

Clinical Studies

Abstract

Nail unit melanoma (NUM) remains a diagnostic challenge both clinically and histopathologically. In melanocytic lesions, melanocytes may be incorporated into the nail plate and are termed melanocyte remnants (MR). The presence of MR provides a diagnostic clue, sometimes the sole clue, of NUM thus careful histopathologic examination of the nail plate is crucial. In our study, we will perform a review of cases of NUM with the presence of MR in the nail plate. We will record the characteristics of MR, including color, size in comparison to adjacent onychocytes, nuclear distribution, and the presence of pigment and retraction artifact. We will collect data on immunoperoxidase staining of MR, and given the variable success demonstrated in prior studies, our study aims to determine the most useful melanocytic marker(s) to detect MR. Techniques and challenges of softening agents used to process nail specimens, and their potential for false-negative results of immunoperoxidase staining, will be discussed. We will compare characteristic findings of MR with those found in nonmelanocytic entities such as onychomycosis, psoriasis, and squamous cell carcinoma. Thus far, our observations have shown that MR are typically larger than adjacent onychocytes, their nuclei are pressed to the periphery, and pigmentation and retraction artifact are often present compared to its mimickers. This information will assist dermatopathologists in recognizing MR and offer a practical screening tool to aid in the diagnosis of NUM. We anticipate this study will provide further evidence that nail plate histopathology is an essential component of routine evaluation of pigmented nail disorders.