Rhabdomyosarcoma in Children: Histologic Subtypes and Prognosis

ABSTRACT

Thirty cases of rhabdomyosarcoma in patients under the age of 15 years were reviewed retrospectively to find out characteristics of histologic subtypes related to prognosis. Histologic diagnosis were embryonal in 21(70%), alveolar in 7(23%) and mixed type in 2(7%). Cellular anaplasia was noted in 6 cases. Round to polygonal cells with abundant eosinophilic cytoplasmic rim or globules were most characteristic cytologic feature or rhabdomyosarcomas, being followed by myofibrils. Myxoid and edematous stroma in embryonal type and alveolar pattern in alveolar type wee nost characteristic growth pattern. Immunohistochemically, tumors were positive for desmin, actin and myoglobin in 97%, 27%, and 40%, respectively. Consequently, characteristic cytologic features are important to differentiate rhabdomyosarcomas form other kinds of small round cell tumor and growth pattern is more critical in categorizing histologic subtypes. Desmin is far more useful than actin or myoglobin in the diagnosis of rhabdomyosarcoma.