PGR and breast carcinoma: The univariate analyses showed that tumor size (either derived from MR image or pathologic result), lymph node metastasis (as seen on MR images or as determined by histopathologic studies), central location of tumor, unilateral nipple enhancement, relationship of tumor to nipple, nipple change, malignant mass pattern, periareolar skin thickening, thickness of NAC enhancement, grade and hormone receptor (ER or PR) positive breast cancer were risk factors related to NAC invasion.