Rhabdomyosarcoma is a malignant mesenchymal tumor with striated muscle differentiation. Most commonly developing in children or adolescents. Previously three subtypes have been described: embryonic, alveolar and pleomorphic. Spindle cell / sclerosing rhabdomyosarcoma is a rare new subtype described in the latest edition of the WHO soft tissue, it develops in children and adults and it is subdivided into 3 genomic groups with different prognosis according to the latest advances in cytogenetics. We report a case of sclerosing rhabdomyosarcoma in a 15-year-old boy with painful swelling of the forearm that has progressed for 3 months. Microscopic examination shows entirely tumor fragments, consisting of an eosinophilic hyaline matrix delimiting tumor lobules and nests, sometimes with a pseudo-vascular and alveolar appearance. Tumor cells have small, irregular and hyperchromatic nuclei with coarse chromatin and eosinophilic cytoplasm. Rare rhabdomyoblast cells are noted. Immunohistochemistry shows expression of Desmine; Myogenin; CD99; Myo D1 and loss of SMA expression.