Nuclear protein in testis midline carcinoma with unusual elevation of α-fetoprotein and synaptophysin positivity: a case report and review of the literature.

Nuclear protein in testis (NUT) midline carcinoma (NMC) is a rare cancer that displays a characteristic chromosomal rearrangement of BRD4-NUT t(15;19)(q14;q13.1). Despite occasional dramatic responses to radiation and chemotherapy, NMC usually behaves aggressively and becomes rapidly progressive. Immunohistochemical staining is usually limited to p63, cytokeratins, and monoclonal NUT antibody. Here, we report a NMC case in a 36-year-old man with elevated serum α-fetoprotein (AFP), synaptophysin positivity, and a 9.0 cm mass involving the right lung and mediastinum. Tumor cells demonstrated BRD4-NUT fusion on fluorescence in situ hybridization. To our knowledge, only one other case with elevated serum AFP and one case with synaptophysin positivity have been described. This diagnosis will undoubtedly grow more common as informed physicians become more aware of the disease and begin testing for NMC. Further study is needed to establish the prevalence of NMC and to elucidate the significance of elevated AFP and synaptophysin positivity in this rare tumor.