A Case of Epithelioid Blue Nevus

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Although epithelioid blue nevus (EBN) is a rare variant of blue nevus that was first reported in patients with Carney complex , which encompasses cardiac and cutaneous myxomas, spotty skin pigmentation, endocrine overactivity, and psammoma-tous melanotic schwannomas, 1 it has been also documented in the absence of such clinical features. 2 Histological characteristics of EBN are variably pigmented, large epithelioid melanocytes with vesicular nuclei and prominent eosinophilic nucleoli and a small number of melanophages that are sometimes associated with a few pigmented, spindle, and dendritic cells. 3 EBN is a diagnostically challenging entity because of its rarity and histo-logical overlap with other pigmented melanocytic lesions, such as cellular blue nevus, malignant blue nevus, and the so-called animal-type malignant melanoma. Because it is very uncommon and no cases have been recorded in the Korean literature, this Korean case is reported. A 21-year-old woman presented with a bluish nodule that had been slowly growing for approximately 10 years on the dorsum of the right foot (Fig. 1A). The lesion was dome-shaped and measured 1.0 cm in diameter. There were no clinical features of Carney complex. The lesion was completely excised. The histological examination showed a relatively well circum-scribed, round nodule with heavy pigmentation in the reticular dermis with extension into the subcutaneous adipose tissue (Fig. 1B). The tumor was composed of heavily pigmented, epitheli-oid melanocytes with vesicular nuclei and prominent nucleoli (Fig. 1C, D). Neither mitotic figures nor infiltrative growth patterns were noted. Melanin pigmentation was variable in the epi-thelioid cells. A small number of fusiform-shaped melanocytes and dendritic spindled melanocytes were also found among the pigmented epithelioid melanocytes. No junctional or dermal banal nevus component was present, and the papillary dermis was spared. The deepest boundary of the tumor was a pushing border with mild fibrosis. Immunohistochemical findings included pigmented epithe-lioid cells positive for S-100 protein (Fig. 2A) and Melan A (Fig. 2B), while only a few cells were reactive for HMB45 (Fig. 2C). A few CD68-positive melanophages were noted (Fig. 2D). These results indicate that almost all pigmented epithelioid cells were epithelioid melanocytes. Ki-67–labeled nuclei were very rare. All of these findings were consistent with EBN. DISCUSSION Blue nevus is a tumor of …