A novel STRN3::PRKD1 fusion in a cribriform adenocarcinoma of salivary gland with high‐grade transformation

Abstract

AbstractCribriform adenocarcinoma of salivary gland (CASG) is a rare form of salivary gland neoplasm that mostly arises from minor salivary glands. We report a case of CASG with high‐grade transformation harboring a novel STRN3::PRKD1 fusion. A 59‐year‐old male presented with a palatal mass. Morphologically, the tumor consisted of two components: solid high‐grade and glandular low‐grade areas. The solid high‐grade area comprised solid nests of high‐grade carcinoma with central necrosis arranged in lobules delineated with prominent stromal septa. The glandular low‐grade area comprised of cribriform and microcystic architecture in a hyalinized and hypocellular stroma. Immunophenotypically, the tumor was positive for S100 but negative for p40 and actin. However, due to the high‐grade component, tissue was sent for salivary gland NGS fusion panel analysis to confirm the diagnosis. The current case illustrates high‐grade transformation in CASG. Furthermore, identification of a STRN3::PRKD1 fusion expands the genetic spectrum of CASG.