USP6 and fibroma: The differential diagnoses in our case, based on the tumor morphology and immunophenotype, included nodular fasciitis, fibroma of the tendon sheath, and spindle cell melanoma. The storiform and short fascicular arrangement with admixed osteoclast-like giant cells in our case mimicked nodular fasciitis and fibroma of the tendon sheath; however, the absence of USP6 gene rearrangement and the dual immunopositivity for S100 and SOX10 argued against both entities, but rather raised consideration for spindle cell melanoma.