NUT carcinoma of larynx with aberrant LCA expression: A rare entity with diagnostic and therapeutic challenge.

Nuclear protein in testis (NUT) carcinoma (NC) are highly aggressive tumors, seen in the head and neck region. These tumors have an undifferentiated to a poorly differentiated morphology, and their diagnosis requires help of ancillary testing by immunohistochemistry (IHC) or in situ hybridization techniques. Here, we describe a case of 27-year-old patient with a rare NC of the larynx. The biopsy from the mass revealed an undifferentiated tumor, which on IHC showed positivity for cytokeratin, p40, LCA, and NUT. In view of NUT positivity, the case was reported as NC of larynx. LCA positivity of the tumor was puzzling and an extensive IHC panel was applied which ruled out the possibility of a hematolymphoid neoplasm. Literature search revealed that an aberrant LCA expression is extremely rare in NCs and could potentially lead to a misdiagnosis. Hence, an elaborative panel in an undifferentiated malignancy is prudent.