What is rhabdomyosarcoma?

Updated: Feb 01, 2019
  • Author: Amelia F Drake, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

Answer

Rhabdomyosarcoma is a malignant tumor of striated muscle origin. According to Rubin, it is derived from primitive mesenchyme that retained its capacity for skeletal muscle differentiation. [1] Rhabdomyosarcoma of the head and neck is primarily a disease of the first decade of life, and it is the most common soft tissue sarcoma in childhood. Approximately 90% of all cases of rhabdomyosarcoma are diagnosed in individuals younger than 25 years, and within this group, 60-70% are younger than 10 years. Rhabdomyosarcoma represents 3.5% of all malignancies in children aged 0-14 years, with approximately 250 new cases diagnosed each year. The annual incidence of rhabdomyosarcoma in the United States is 4.5 cases per 1 million children younger than 14 years.

The disease has little propensity for any particular geographic location or ethnic group. However, people of Asian descent have a slightly lower prevalence than that of blacks or whites. The male-to-female ratio is approximately 1.5:1.

See the image below.

Embryonal rhabdomyosarcoma is evidenced by a varia 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.

The head and neck are reportedly the most frequent (35-40%) sites of origin, followed by the genitourinary tract, extremities, trunk, retroperitoneum, and uncommon regions (eg, intrathoracic, GI tract, perianal and anal regions). However, a retrospective study by Ma et al of pediatric patients with rhabdomyosarcoma found the genitourinary system to be the most common primary tumor site (43.5%), with the head and neck being the second most common (31.1%) and the extremities the third most common (11.2%); 6.2% of primary tumors were found in the retroperitoneum. [2]

In the head and neck, the most common sites of rhabdomyosarcoma are parameningeal and orbital locations, which account for 16% and 9% of all cases of the disease, respectively. Over several decades, great progress has been made in the treatment of rhabdomyosarcoma. As a result, 5-year survival rates increased from 25% in 1970 to 73%, as shown in the Intergroup Rhabdomyosarcoma Study (IRS)-IV reported in 2001. [3]

In a retrospective study of 28 pediatric patients with head and neck rhabdomyosarcoma published in 2018, Häußler et al found the 5-year overall survival rate to be 91.3%, with the median period of progression-free survival reported to be 46 months. Patients received multimodal treatment, including polychemotherapy (all patients), adjuvant radiation therapy (24 patients), and surgery (12 patients). [4]

In 2006, the National Collaborating Centre for Cancer published a guideline for improving outcomes in patients with sarcoma. [5]  Additionally, the National Cancer Institute has provided a patient guide to treatment. [6]


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