As a result, the World Health Organization currently takes into account both molecular genetics and morphology to classify rhabdomyosarcoma into the embryonal, alveolar, spindle cell/sclerosing, and pleomorphic subtypes.When examining Embroynal Rhabdomyosarcoma tumors vs. Alveolar Rhabdomyosarcoma tumors, a 2013 study had discovered that there were more rates of mutation in ERMS tumors. The study had use whole genome sequencing to sequence the DNA from 16 RMS tumors and found that RAS pathway mutations tend to be more associated with intermediate and high risk embryonal Rhabdomyosarcoma. Additionally, Embryonal Rhabdomyosarcoma tends to be more common in males versus females, with an occurrence of 1.4:1. Histology
Embryonal rhabdomyosarcoma has been informally classified as a "small round blue cell tumor" because of the characteristic microscopic appearance of its cells after histological staining with hematoxylin and eosin. Histologically, embryonal rhabdomyosarcoma commonly presents as alternating loose and dense patches of cells, including round cell and spindle cell components. The heterogenous structure resembles striated muscle at various embryonal developmental stages. Location
Embryonal rhabdomyosarcoma can develop in soft tissues throughout the body, however, it is commonly found in the "head and neck area or in the genital or urinary organs"  The botryoid variant of ERMS occurs in mucosal-lined organs such as the common bile duct, bladder, and vagina. The etymology for this variant name comes from "grape clusters", referring to the gross appearance of grape-like masses. Epidemiology of RMS
RMS has a higher incidence of affecting males compared to females.
In either case, "fusion-negative" alveolar rhabdomyosarcoma have similar clinical presentation and outcome as embryonal rhabdomyosarcoma, thus risk stratification, prognosis, and treatment intensity of rhabdomyosarcoma are now determined by fusion-status instead of histological classification. Imaging
After a physical exam, formal diagnosis of RMS in adult patients requires a computed tomography (CT) scan, which can assess the areas affected and to delineate the tumor. In children, physicians may opt for magnetic resonance imaging (MRI) to limit radiation exposure in younger populations. In the majority of individuals diagnosed with rhabdomyosarcoma, more than half are diagnosed before the age of 10. Prognosis
The prognosis for rhabdomyosarcoma has improved greatly in recent decades, with over 70% of people surviving for five years after diagnosis. The combined use of radiotherapy and surgery has significantly reduced the mortality rates compared to patients who did not undergo any radiotherpay or chemotherapy treatments. Embryonal rhabdomyosarcoma is generally associated with better prognosis than alveolar rhabdomyosarcoma, with a 5-year survival prognosis of 82% and 53%, respectively. This may be due to the more aggressive and metastatic nature of ARMS that can be attributed to its PAX3–FOXO1 or PAX7–FOXO1 gene fusions. Nevertheless, some embryonal rhabdomyosarcoma patients with a rare Leu122Arg mutation in MYOD1 gene have a very poor outcome. In two different studies, none of the subjects with the MYOD1 mutation survived. Tumors due to this mutation commonly manifest in the head and neck area, causing the mutated protein to behave like an oncogene.There have not been many studies linking the genetic profile and clinical outcome of ERMS.