LAUSR

The histopathology showed slight epidermal hyperplasia (figure 1B). In the deep dermis and subcutaneous tissue, there was prominent proliferation of apocrine ducts and glands, which revealed the characteristic decapitation of an inner secretory layer and a flattened outer layer of myoepithelial cells (figure 1C, D). According to the clinical and histopathological features, apocrine nevus was diagnosed. Apocrine nevus is a hamartoma arising from proliferation of mature apocrine glands. Some authors have used apocrine nevus and apocrine hyperplasia interchangeably, while others argue for their separation. Requena et al. [1] described that apocrine nevus is different from apocrine hyperplasia because apocrine nevus is usually of a large size and cannot involute. However, Kazakov et al. [2] used the two names interchangeably based on the subjective assessment of lesion size and the notion that it is probably related to stage of the lesion. Apocrine nevus has a tendency to arise in regions where apocrine glands are distributed, especially the axillae [3, 4], but it can also occur on other locations without apocrine glands, such as the cheeks [5], chest [6] and abdomen [7]. Apocrine nevus is rare and can present as various clinical presentations, such as papules, nodules or large masses [4], therefore, the diagnosis can only be confirmed with histopathology. Histopathologically, apocrine nevus exhibits hyperplasia of apocrine glands. The glands are excessive in number, arranged in vague lobules, and have an appearance similar to that of normal apocrine glands (figure 1B-D) [3–7]. In one report, apocrine nevus was shown to occur with nevus sebaceous [8], however, the location and appearance of the lesion was typical of nevus sebaceous. In our current case, the lesion on the lower abdomen was congenital, and there were no signs of nevus sebaceous histologically. According to these characters, the diagnosis of apocrine nevus was confirmed.