A morphologic and immunohistochemical appraisal of invasive breast carcinomas with neuroendocrine differentiation.

Abstract

Background: Invasive breast carcinomas with neuroendocrine differentiation (IBCNED) are a heterogenous group of tumours first recognised, as a distinct entity, by the World Health Organisation (WHO) in 2003. The classification of these tumours has undergone significant changes since they were first described, and the diagnostic criteria has been inconsistent amongst reporting authors. IBCNED have not been studied in the South African context, and this study aims to review the incidence, demographic profile, histopathology and immunohistochemical profile of IBCNED. Materials and Methods: A three-month retrospective study of cases with the diagnosis of invasive breast carcinomas was undertaken to determine the clinicopathologic profile of IBCNED. Results: The mean age of female patients with IBCNED was 55 years. Thirty-five (35/91, 38%) cases were positive for synaptophysin and/or chromogranin A. The tumours showed a histomorphology comparable with invasive breast carcinoma of no special type and were predominantly (33/35, 94%) moderately to poorly differentiated. The predominant molecular subtype, with 91% (33/35), was luminal B . Conclusion: IBCNED show a diverse range of histomorphologic features, similar to those seen in conventional breast carcinomas of no special type, however they do have distinct cytomorphological characteristics and show a predilection for luminal B molecular subtype. A larger cohort is necessary to confirm these findings and to expand knowledge and treatment options.