Hutchinson Sign: Biopsy May Assist in Diagnosis of Subungual Melanoma in Situ

BACKGROUND Early and accurate diagnosis of subungual melanoma (SUM) through histopathologic examination is critical, but lack of clinical suspicion leads to delays in diagnosis. Hutchinson sign (HS) can be one of the important clinical indicators for diagnosing SUM. OBJECTIVE To evaluate the diagnostic value of small biopsies of HS for detecting SUM in situ. METHODS We retrospectively evaluated 12 patients who were diagnosed as SUM in situ and underwent punch biopsy at HS areas. Clinical features, dermoscopic findings, and histopathologic findings in HS regions were analyzed. RESULTS In most cases, HS was seen in hyponychium (11/12, 91.7%) with 1 case found in proximal nail fold, and 1 case in both the hyponychium and proximal nail fold. Dermoscopic features of HS showed irregular diffuse pigmentation (12/12, 100%) and parallel ridge pattern (7/12, 58.3%). Histopathologically, all cases showed irregularly scattered atypical melanocytes with hyperchromatic nuclei. Two cases showed subtle changes in melanocytes with little nuclear atypia, but additional section specimen showed more definitive findings of SUM in situ. CONCLUSION We present a supplementary biopsy technique for diagnosing SUM. Biopsy of HS may help in the diagnosis of SUM.