USP6 is a hominoid-specific deubiquitinase enzyme located on chromosome 17 that functions as an ATP-independent isopeptidase cleaving ubiquitin moieties and regulating its own deubiquitination 1. It promotes plasma membrane localization of ARF6 and selectively regulates ARF6-dependent endocytic protein trafficking, with potential roles in intracellular trafficking and inflammatory signaling 1. Clinically, USP6 is most significant as a molecular marker for benign mesenchymal neoplasms rather than for its intrinsic biochemical function. USP6 gene rearrangements—including promoter-swapping fusions with various partners (SPTAN1, TMP4, SPARC, EIF5A, and others)—define a family of typically benign, self-limiting fibroblastic/myofibroblastic tumors 12. This spectrum includes aneurysmal bone cysts, nodular fasciitis, myositis ossificans, fibroma of tendon sheath, and fibro-osseous pseudotumor of digits 34. USP6 rearrangements have high diagnostic utility: FISH analysis for USP6 demonstrates 86% sensitivity and 100% specificity for confirming nodular fasciitis diagnosis, with 100% positive predictive value 5. Molecular identification of USP6 fusions is essential in routine diagnostics to prevent misdiagnosis of these benign lesions as malignancies and to understand biological behavior 26.