NFIB::PHACTR2, a novel atypical fusion gene identified in adenoid cystic carcinoma of the palate

Adenoid cystic carcinoma (ACC) is the second most common malignancy of salivary glands with a poor long-term prognosis. The presence of mutually exclusive t(6;9)/MYB::NFIB and t(8;9)/MYBL1::NFIB chromosomal translocations has been used as diagnostic markers for ACC. In this study, we report a non-MYB/MYBL1 fusion gene NFIB::PHACTR2 in a palate ACC of a 66-year-old male. The excised 1.7 cm partially encapsulated tumor featured focal invasion into the adjacent mucinous minor salivary glands. By light microscopy, the tumor showed cribriform and tubular patterns with obvious perineural and intraneural invasion. The findings remind us that salivary gland tumors without MYB/MYBL1 fusion genes could still be ACC if they have a rearrangement involving genes adjacent to MYB/MYBL1 genes.