Rhabdomyosarcoma classification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Shadan Mehraban, M.D.[2]

Overview

The international classification of rhabdomyosarcoma (RMS) was created by the Intergroup Rhabdomyosarcoma Study group (IRSG). The four main subgroups include: Embryonal rhabdomyosarcoma (ERMS), Alveolar rhabdomyosarcoma (ARMS), Botryoid and spindle cell (leiomyomatous) RMS, Sclerosing and spindle cell RMS. The other separate categories for subtypes which do not classify into above groups are Undifferentiated, Pleomorphic/anaplastic, and Sarcoma, not otherwise specified (NOS).

Classification

The international classification of rhabdomyosarcoma (RMS) was created by the Intergroup Rhabdomyosarcoma Study group (IRSG) therapeutic trials (IRS-I to IV).^[1]^[2]
The four main subgroups are:
- Embryonal rhabdomyosarcoma (ERMS)
- Alveolar rhabdomyosarcoma (ARMS)
- Botryoid and spindle cell (leiomyomatous) RMS
- Sclerosing and spindle cell RMS
Separate categories for other subtypes which do not classify into above groups:^[3]
- Undifferentiated
- Pleomorphic/anaplastic
- Sarcoma, not otherwise specified (NOS)


RMS subtypes	Definition
Embryonal rhabdomyosarcoma (ERMS)	The most common group Contains 59% of all RMS Intermediate prognosis Mostly occurs in head, neck, and genitourinary system^[4] Larger peak between age of 0-5 years and smaller peak among adolescents Specific translocation is not yet designated^[5] Loss of heterozygosity (LOH) at the 11p15 locus, the site of the IGF-2 gene
Alveolar rhabdomyosarcoma (ARMS)	Determined by FOXO1 rearrangement, t (1;13) or t (2;13)^[6] Poorer prognosis Contains 21% of all RMS More likely among adolescents Mostly occur in the trunk and extremities
Botryoid and spindle cell RMS	Botryoid RMS contain 6% of all RMS Spindle cell RMS contains 3% of all RMS Less common variants of ERMS Accompanied with more favorable prognosis Botryoid name related to grape-like appearance of tumor Botryoid RMS occur within bladder wall and vagina Spindle cell is prevalent among infants and neonates under age of 1 years old Spindle cell RMS occurs in paratesticular location
Sclerosing RMS	Less common variants of ERMS Poor outcome Mostly occurs after age of 1 years old Could also be seen among adults Accompanied with MyoD1 mutation
Anaplastic RMS	Mostly seen in patients with Li-Fraumeni syndrome^[7] Contain 1% of all cases Defined as a large hyperchromatic nuclei

References

↑ Qualman SJ, Coffin CM, Newton WA, Hojo H, Triche TJ, Parham DM; et al. (1998). “Intergroup Rhabdomyosarcoma Study: update for pathologists”. Pediatr Dev Pathol. 1 (6): 550–61. PMID 9724344.
↑ Hicks J, Flaitz C (2002). “Rhabdomyosarcoma of the head and neck in children”. Oral Oncol. 38 (5): 450–9. PMID 12110339.
↑ Kodet R, Newton WA, Hamoudi AB, Asmar L, Jacobs DL, Maurer HM (1993). “Childhood rhabdomyosarcoma with anaplastic (pleomorphic) features. A report of the Intergroup Rhabdomyosarcoma Study”. Am J Surg Pathol. 17 (5): 443–53. PMID 8470759.
↑ De Giovanni C, Landuzzi L, Nicoletti G, Lollini PL, Nanni P (2009). “Molecular and cellular biology of rhabdomyosarcoma”. Future Oncol. 5 (9): 1449–75. doi:10.2217/fon.09.97. PMID 19903072.
↑ Scrable HJ, Witte DP, Lampkin BC, Cavenee WK (1987). “Chromosomal localization of the human rhabdomyosarcoma locus by mitotic recombination mapping”. Nature. 329 (6140): 645–7. doi:10.1038/329645a0. PMID 3657988.
↑ Helman LJ, Meltzer P (2003). “Mechanisms of sarcoma development”. Nat Rev Cancer. 3 (9): 685–94. doi:10.1038/nrc1168. PMID 12951587.
↑ Hettmer S, Archer NM, Somers GR, Novokmet A, Wagers AJ, Diller L; et al. (2014). “Anaplastic rhabdomyosarcoma in TP53 germline mutation carriers”. Cancer. 120 (7): 1068–75. doi:10.1002/cncr.28507. PMC 4173134. PMID 24382691.

Overview