Background: NUT carcinoma is a rare aggressive squamous cell carcinoma subtype genetically characterized by NUTM1 rearrangements. NUT carcinoma can be easily misdiagnosed as an undifferentiated carcinoma or Ewing sarcoma due to its primitive differentiation.
Case presentation: We report a case of renal-derived NUT carcinoma diagnosed as a malignant small round-cell tumor resembling Ewing sarcoma/primitive neuroectodermal tumor where the diagnosis was revised to NUT carcinoma with a characteristic NUTM1 rearrangement based on next-generation sequencing (NGS). The patient received a standard NUT carcinoma treatment after recurrence but died of first-line chemotherapy failure due to advanced neoplasm progression.
Conclusion: Routine NUT immunohistochemistry staining, NGS, and/or fluorescent in situ hybridization for poorly differentiated carcinoma and sarcoma can help avoid misdiagnosis of NUT carcinoma-related tumors, allowing patients to benefit from bromodomain and extra-terminal motif inhibitor therapy.
Keywords: Carcinoma; NUTM1; diagnosis; kidney; sarcoma.
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