Answer
Biologic factors can also influence prognosis. The literature often mentions that the alveolar subtype of rhabdomyosarcoma is associated with a prognosis worse than that of the other types. When the alveolar subtype is compared with the embryonal type, alveolar rhabdomyosarcoma is more common in patients with less favorable clinical features (eg, older age, extremity involvement, distant metastasis). However, when the IRS-I and IRS-II study groups were evaluated, no statistical difference was noted among subtypes when examined independently of other factors.
Cellular DNA content, or ploidy, does appear to have prognostic significance. Patients whose tumor cells have a DNA content 1.5 times higher than normal (hyperdiploid) have a better outcome than those with normal (diploid) or twice-normal (tetraploid) DNA content. Hyperdiploid DNA content is associated with embryonal histology, whereas tetradiploid DNA content is associated with alveolar histology. Also, the incidence of anaplasia in patients with rhabdomyosarcoma may be higher than previously described and may be of prognostic significance in children with intermediate-risk rhabdomyosarcoma, as its presence appears to negatively influence survival. [16]
In a study of 100 patients under age 21 years (median age 4 years) with large, nonmetastatic primary nongenitourinary embryonal rhabdomyosarcoma of the abdomen, Dantonello et al concluded that children with these tumors have a fair prognosis if tumor resection or irradiation can be performed after induction chemotherapy. In the study, 36 patients underwent resection following induction chemotherapy, and 60 tumors were irradiated. Median follow-up was 10 years, with patients demonstrating 5-year event-free and overall survival rates of 52% and 65%, respectively. According to the investigators, significant patient risk factors included age over 10 years, failure to achieve complete remission, and inadequate secondary local therapy (ie, incomplete secondary resection or absence of radiation therapy). [17]
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Embryonal rhabdomyosarcoma is evidenced by a variable cell population consisting of small, round tumor cells with hyperchromatic nuclei and of large, polygonal-shaped tumor cells with abundant eosinophilic cytoplasm, which often contains diagnostic cross striations (arrow). Image provided by Scott Kilpatrick, MD, Department of Pathology, University of North Carolina Hospitals.
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Alveolar rhabdomyosarcoma is evidenced by uniform cell population consisting of cells with a high nuclear-to-cytoplasmic ratio. The cells are arranged in variably sized nests separated by fibrous tissue septa. In places, the cells appear loosely dispersed, mimicking a pulmonary alveolar pattern. Image provided by Scott Kilpatrick, MD, Department of Pathology, University of North Carolina Hospitals.
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Axial CT scan of rhabdomyosarcoma in the left middle ear. Image provided by Suresh Muhkerji, MD, Department of Radiology, University of North Carolina Hospitals.
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Axial CT scan of left orbital rhabdomyosarcoma. Image provided by Suresh Muhkerji, MD, Department of Radiology, University of North Carolina Hospitals.
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Axial CT scan of right masticator space rhabdomyosarcoma. Image provided by Suresh Muhkerji, MD, Department of Radiology, University of North Carolina Hospitals.
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MRI of right masticator space rhabdomyosarcoma. Image provided by Suresh Muhkerji, MD, Department of Radiology, University of North Carolina Hospitals.
