Extrapulmonary neuroendocrine small and large cell carcinomas: a review of controversial diagnostic and therapeutic issues

Summary Extrapulmonary neuroendocrine carcinoma (EPNEC) is a heterogeneous and rare group of high-grade neoplasms occurring in different organs. They usually share a poor prognosis, but diagnostic and therapeutic options still include several controversial issues, due to the rarity of this condition and to differences in architecture and cell size, being some cases pure small cell carcinomas, other pure large cell neuroendocrine carcinomas and some others combined/mixed neuroendocrine carcinomas with a conventional non-neuroendocrine carcinoma. In addition, the therapeutic strategy varies in different organs (surgery and/or chemotherapy and/or radiation therapy and/or targeted treatments), and clinicians and pathologists are asked to interact to reach an accurate classification of every single case, as well as the most appropriate selection of the treatment options, even considering different time points of each EPNEC natural history. This overview highlights controversial pathological and clinical issues and summarizes possible solutions to most of such EPNEC-related problems.