A unique presentation of eccrine hamartoma: eccrine nevus with abnormal eccrine structures and angiomyxoid stroma.

Eccrine hamartomas are very rare lesions usually presenting in early childhood, with variable clinical presentations. Local hyperhidrosis is often noticed. These lesions are all characterized by an increase in number and/or size of normal eccrine glands. We report the case of a hamartomatous lesion composed of eccrine structures and prominent angiomyxoid stroma, diagnosed in a 9-year-old girl. In this lesion, eccrine structures were not normal eccrine coils or ducts but ramified strands of small eosinophilic cells, containing a few eccrine ducts. These epithelial structures expressed carcinoembryonic antigen, cytokeratin 14, and cytokeratin 77, in a pattern suggesting ductal eccrine differentiation. The mesenchymatous component contained numerous capillary vessels in an abundant myxoid stroma. It was organized concentrically around the epithelial structures. This angiomyxoid stroma was somewhat reminiscent of mucinous eccrine nevi and eccrine angiomatous hamartomas. We propose to describe this unique lesion inside the group of eccrine nevi with the term "angiomyxoid eccrine nevus."