Abstract:

Objective To study the pathologic characteristics of childhood rhabdomyosarcoma. Methods Thirty cases of pediatric rhabdomyosarcoma were reviewed by histological and immunohistochemical observation. Results There were 22 boys and 8 girls. Histologically, all the cases were divided into embryonal, alveolar, and spindle/sclerosing rhabdomyosarcoma types, in which, embryonal type accounted for 66.67% (20/30); alveolar type, 26.67% (8/30); and spindle/sclerosing type, 6.67% (2/30). The location of the tumors included the trunk （50%, 15/30), head and neck (23.33%, 7/30), extremities (20%, 6/30), and urinary system (6.67%, 2/30). Immunohistochemical staining findings indicated that muscle-specific actin (MSA), smooth muscle actin (SMA), Desmin, myogenin (MyoG), and MyoD-1 had different degrees of positive expression. Conclusion Embryonal, alveolar, and spindle cell/sclerosing rhabdomyosarcoma are main histological types of rhabdomyosarcoma of children. They mainly show primitive small round cells with rhabdomyoblast cells in some cases. Tumor cells express different levels of muscle origin marks such as MSA, SMA, Desmin, MyoG, and MyoD-1. Differential diagnosis should be made with neuroblastoma and peripheral primitive neural ectoderm tumor.

Key words: soft tissue tumors, rhabodmyosarcoma, pathology, immunohistochemistry