Aims: To clarify the clinicopathological significance of breast neuroendocrine ductal carcinoma in situ (NE-DCIS), i.e. DCIS in which >50% of cells immunohistochemically express NE markers (chromogranin A and/or synaptophysin), 20 NE-DCIS were studied and the findings compared with those of 274 non-NE-DCIS.
Methods and results: NE-DCIS accounted for 6.8% of all DCIS. Mean patient age was 50.4 years for NE-DCIS and 49.6 years for non-NE-DCIS (P = 0.66). The main clinical presentation of NE-DCIS was a bloody nipple discharge, seen in 72%, significantly different from the 5% in non-NE-DCIS cases (P < 0.01). Carcinoma was preoperatively diagnosed in 67% of NE-DCIS and 95% of non-NE-DCIS cases (P < 0.01). NE-DCIS was histologically characterized by a predominantly solid growth of cancer cells with fine-granular cytoplasm and ovoid, or occasionally spindle-shaped nuclei. A well-developed vascular network was also common. Nuclear grades and Van Nuys classification were significantly lower for NE-DCIS than for non-NE-DCIS (P < 0.01). The mean MIB-1 labelling index was 4.3% in NE-DCIS and 8.1% in non-NE-DCIS (P < 0.01). Furthermore, NE-DCIS cases had significantly higher oestrogen and progesterone receptor and lower HER2 scores than non-NE-DCIS cases (P < 0.01).
Conclusions: NE-DCIS has characteristic clinicopathological features and can, therefore, be regarded as a distinct variant of DCIS.