Expanding the genetic landscape of seromucinous hamartoma: novel HMGA2::PHF14 gene fusion - a case report.

Seromucinous hamartomas (SH) are benign polypoid proliferations of small eosinophilic glands arising in the sinonasal tract. Together with respiratory epithelial adenomatoid hamartoma (REAH), they form a morphological continuum, and their hamartomatous designation has been increasingly questioned. Some authors now consider them stationary precancers potentially linked to tumor development through atypical sinonasal glands arising via the SH pathway. The molecular genetic background of SH remains poorly characterized, with no recurrent genetic alterations identified and no unequivocal molecular signature established to date. Here, we present a case of a 68-year-old woman with SH exhibiting a distinctive immunohistochemical staining pattern and a novel HMGA2::PHF14 fusion. This finding raises further questions about the true nature of a subset of SHs and underscores the need for thorough molecular characterization of these rare lesions.