Breast intracystic papillary carcinoma: an update

Intracystic papillary carcinoma (IPC), a breast tumor mainly occuring in the elderly, has long been considered as a variant of ductal carcinoma in situ (DCIS). This is now debated since metastatic cases have been reported. In this study, surgical pieces of 20 IPCs were reassessed, and markers of myopepithelial layer (p63, CD10 and Smooth Muscle Actin) as well as estrogen receptors (ER) and progesterone receptors (PgR) and C-erb-B2 oncoprotein expression were systematically performed and quantified. In 10 cases, an associated unequivocal invasive component was found. In all 20 cases, no myoepithelial layer was found. Eighteen tumors were ER positive, 14 were PgR positive. Moreover, none of the tumors over-expressed C-erb-B2 oncoprotein. Therefore this study showed that in all cases of IPC there were microscopic features of invasive carcinoma despite good clinical prognostic indicators, and that precise characterization of tumors requires extensive paraffin embedding of surgical pieces.