We report, for the first time, a case of pure NE breast carcinoma (NEBC) exhibiting all of the World Health Organization (WHO)-categorized morphological and phenotypic NE features (i.e., round solid nests of spindle cells, plasmacytoid cells, large clear or mucinous signet-ring cells with a peripheral palisading tendency and immunohistochemical positivity for the NE markers synaptophysin and chromogranin in more than 50% of the tumor cell population) along with synchronous abdominal non-Hodgkin’s lymphoma. This evidence concerns the gene SYP and non-Hodgkin lymphoma.