Apocrine encapsulated papillary carcinoma (EPC) of the breast is a rare neoplasm,
and only 10 cases have been reported in the literature to date. Although EPC by definition
lacks a peripheral myoepithelial layer, all previously published apocrine EPC cases
were clinically indolent and lacked a conventional invasive component. Herein, we
report the 11th case of apocrine EPC, which had a conventional invasive carcinoma
component and provides evidence of the malignant potential of this entity. We postulate
that apocrine EPC is most likely a morphological variant of conventional EPC, with
the same unpredictable malignant potential as non-apocrine cases.