Congenital apocrine hamartoma: an unusual clinical variant of organoid nevus with apocrine differentiation.

Congenital apocrine hamartomas are rare tumors of the skin composed of mature apocrine glands in the papillary and reticular dermis. Several cases have been reported in the literature but few were of uniform clinical appearance. The term apocrine nevus has been used interchangeably with apocrine hamartoma in the literature, however, based on their distinctive morphologies we believe they are different entities. We describe a 7-year-old girl with a congenital apocrine hamartoma of the left cheek. A stained biopsy specimen from the lesion revealed large mature apocrine glands with decapitation secretion in the dermis. The presence of periodic acid-Schiff-positive, diastase-resistant granular material in the apical cytoplasm of some secretory cells helped differentiate these as apocrine glands. We think this lesion may represent a form of organoid nevus with pure apocrine differentiation.