A novel fusion of EWSR1::PRKD1 in cribriform adenocarcinoma of salivary glands: A rare case report

Cribriform adenocarcinoma of the salivary glands (CASG) represents an underappreciated epithelial malignancy characterized by distinctive histologic patterns and recurrent PRKD gene fusions. We report a novel case of CASG in a 62-year-old female presenting with a 13-month indolent tongue lesion. Histopathological examination revealed neoplastic proliferation with cribriform, solid, and papillary architectural patterns, notable for prominent clear cell morphology. Immunohistochemical profiling demonstrated strong positivity for cytokeratins, PRKD1, p63, and p21, while remaining negative for p40, TTF-1 and myoepithelial markers. Fluorescence in situ hybridization confirmed PRKD1 and EWSR1 gene rearrangement using the corresponding break-apart probes, and next-generation sequencing identified a novel EWSR1::PRKD1 fusion—the first reported instance of this genetic alteration in CASG. This fusion expands the molecular spectrum of CASG beyond previously documented PRKD gene rearrangements and hotspot mutations. Complete surgical excision achieved excellent oncologic control with no recurrence over 38 months of follow-up.