From Serous Tubal Intraepithelial Carcinoma to Neuroendocrine Carcinoma: Molecular Dissection of a Rare Fallopian Tube Carcinoma.

Primary neuroendocrine carcinoma (NEC) of the fallopian tube is exceptionally rare, with only a small number of cases reported. We report an unusual case in a 77-yr-old woman where a fallopian tube was involved by serous tubal intraepithelial carcinoma (STIC), a small component of high-grade serous carcinoma (HGSC), and a predominant component of small cell neuroendocrine carcinoma (SCNEC). Molecular analysis of microdissected different elements supported a clonal origin, with both tumor components (STIC/HGSC and SCNEC) displaying homologous recombination deficiency and a shared TP53 mutation, while the neuroendocrine component uniquely exhibited 4q deletion and additional DNA repair gene mutations in PALB2 and CHEK2 .