Vimentin-positive and Alpha-fetoprotein-elevated Nuclear Protein of the Testis Midline Carcinoma: A Case Report and Review of the Literature.

Nuclear protein of the testis (NUT) midline carcinoma (NMC) is a rare malignant tumor expressing NUT with BRD4/3 rearrangements and is sometimes misdiagnosed as germinoma, especially in alpha-fetoprotein (AFP)-elevated cases. A 28-year-old man had a mediastinal tumor with multiple bone metastases and elevated AFP levels. Imaging/laboratory findings led to a pathological diagnosis of extragonadal germinoma. After unsuccessful treatment with etoposide-cisplatin, he was re-diagnosed with sarcoma due to vimentin-positive findings. He was treated with adriamycin-ifosfamide, which resulted in disease-control. A posthumous examination clarified the NUT rearrangement. Even in cases with characteristic findings, such as elevated AFP levels and vimentin positivity, NMC should be considered as a differential diagnosis. We note, however, that adriamycin-ifosfamide has some efficacy in such cases.