NUTM1 and nut midline carcinoma: Our experience has shown that the identification of the following clues may suggest a diagnosis of NMC; overt pearl formation including a dyskeratocyte, stratification, and cytoplasmic fine vacuoles, especially in cases where the initial suspected diagnosis was “undifferentiated or poorly differentiated carcinoma with little pleomorphism.” Furthermore, the identification of this entity is critical, and immunohistochemistry or FISH studies should be considered for the identification of NUT gene rearrangements.