Molecular landscape of hidradenoma and hidradenocarcinoma: associations with morphology and biology.

Abstract

Our knowledge of the genomic landscape of hidradenocarcinoma (HACa), a rare, malignant sweat gland tumour that can arise de novo or from its benign counterpart, hidradenoma (HA), remains uncertain, and distinguishing between them can sometimes be challenging, as they can both present with conventional, clear cell or poroid morphology. To compare the molecular landscape of HACa to HA and explore what drives their morphological spectrum, we performed whole-exome sequencing and/or RNA sequencing on the largest international cohort of formalin-fixed, paraffin-embedded cases to-date. Our analysis demonstrated the key role of fusion genes in driving both tumourigenesis and morphological subtypes of HACa and HA, and we identified additional molecular drivers of de novo HACa.