CHCHD7 (coiled-coil-helix-coiled-coil-helix domain containing 7) is a mitochondrial protein belonging to the twin CX9C protein family. Structurally, CHCHD7 contains a conserved CHCH domain stabilized by two disulfide bonds and a third helix that interacts hydrophobically with an extension of helix α2 1. Upon reduction of disulfide bonds, CHCHD7 becomes unstructured and aggregates, suggesting a model where protein recognition occurs when CHCHD7 is partially embedded in the mitochondrial outer membrane import pore during Mia40-dependent import 1. While its precise biological function remains unknown, CHCHD7 has been identified as a recurrent fusion partner of PLAG1 in pleomorphic salivary adenomas and other mesenchymal tumors 2. CHCHD7-PLAG1 fusions result from cytogenetically cryptic intrachromosomal 8q rearrangements, with breakpoints in the 5'-noncoding regions leading to PLAG1 promoter swapping and oncogenic overexpression 2. These fusions have been documented in salivary gland pleomorphic adenomas, soft tissue tumors, and uterine sarcomas 34567. The clinical significance relates to tumor classification and prognostication, as CHCHD7-PLAG1 fusion detection helps distinguish neoplastic subtypes with distinct morphologies and biological behaviors.