Immunohistochemical analysis showed strong diffuse positivity for CD99, alongside vimentin, BCL2, Cyclin D1, and C-Kit expression, while markers such as CK7, CK20, S100, and CD34 were negative, effectively ruling out differential diagnoses such as rhabdomyosarcoma, lymphoma, and other SRCTs [21,22]. This evidence concerns the gene CD99 and lymphoma.