Mammary neuroendocrine carcinoma with mucinous differentiation: a clinicopathological study of 15 cases.

BACKGROUND

Mammary neuroendocrine carcinoma (NEC) displays morphological features including mucinous type.

OBJECTIVE

To describe clinicopathological of NEC with mucinous differentiation.

METHODS

A total of 15 cases of mammary NEC with mucinous differentiation were reviewed.

RESULTS

All patients in this study were women aged from 37 to 78 year olds (median 68.1 years). The tumors ranged in size from 1.2 cm to 16 cm (mean 3.74 cm). The amount of extracellular mucin varied from 10% to 90%. Histological grade was I in 7 cases and II in 8 cases. Immunohistochemically, estrogen receptor (ER) and progesteron receptor (PR) were expressed in 12 and 14 cases, respectively. All tumors were negative for Her-2. Ki-67 proliferative index was lesser than 1% in all cases and no cases had demonstrated p53 overexpression. Three patients died of disease with a follow-up of 3 to 6 months. One patient was alive with metastasis at 96 months. Ten patients were disease free (follow-up range from 15 to 125 months).

CONCLUSIONS

Mammary NEC with mucinous differentiation affects mostly older women. All tumors were low grade and immunoreactive for ER/PR and negative for Her-2. Mammary NEC with mucinous differentiation seems associated with well survival parameters.