Overview Flashcards
What are the two incidence age peaks of RMS and their associated histologies?
2–6 yo (embryonal) and 15–19 yo (alveolar)
What is the estimated overall annual incidence of RMS in the United States?
350 cases/yr of RMS in the United States, 3% of all childhood cancers (#1 STS)
What are the most common sites of RMS? List them in order of approximate frequency in %.
Most common sites of RMS:
- H&N 40% (PM 25%, orbit 9%, non-PM 6%)
- GU 30%
- Extremity 15%
- Trunk 15%
What are the most common sites of mets?
Bone, BM, and lung
What % of pts present with mets? What types are prone to have hematogenous mets?
15% of pts present with mets. The prostate, trunk, and extremities are prone to hematogenous mets
What is the most common origin of RMS?
Mesenchymal stem cells. Sporadic RMS is the most common.
What genetic syndromes are associated with RMS?
Beckwith–Wiedemann syndrome (BWS), Li Fraumeni, NF-1, Costello syndrome, and Noonan syndrome
What are the 4 major histologies of RMS and their associated subtypes (if any)? Which is most common?
Major histologies of RMS and subtypes:
- Embryonal (classic, spindle cell, and botryoid) (Most common: 60%)
- Alveolar
- Pleomorphic
- Undifferentiated
What genetic change is associated with embryonal RMS?
LOH 11p15.5 (embryonal) is associated with IGF2 gene deletion, seen in BWS
Also, abnormalities in chromosomes 2, 8, 12, and 13 are associated with MYCN, MDM2, CDK4, CDKN2A (p16), CDKN2B(p15INK4b), and TP53 genes.
What translocations are associated with alveolar RMS? What are the genes involved in the fusion?
Alveolar RMS is associated with t(2;13) (70%) and t(1;13) (20%).
Genes involved are PAX3 or PAX7 with FOXO1 (aka FKHR).
Which is the most common histology of RMS in infants? Young children? Adolescents? Adults?
Most common RMS histology (by age group):
Infants: botryoid
Young children: embryonal
Adolescents: alveolar
Adults: pleomorphic
Which histologies are most commonly associated with each organ site (H&N, GU, extremities/trunk)?
Most common RMS histologies (by site):
H&N: embryonal
GU: botryoid
Extremities/Trunk: alveolar
What is the most important histologic tumor marker for RMS?
MyoD (and other myogenic proteins: actin, myosin, desmin, myoglobin)
What is the DDx for small round blue cell tumors of childhood?
Small round blue cell tumors of childhood:
Lymphoma
EWS
Acute lymphoblastic leukemia
RMS
NB
Neuroepithelioma
MB
Retinoblastoma
(Mnemonic: LEARN NMR)
List the histologies of RMS in terms of prognosis from best to worst.
- Spindle cell and botryoid
- Classic embryonal
- Alveolar
- Undifferentiated
What are the 5-yr OS rates for each of the histologic subtypes?
5-yr OS (by histology):
Botryoid: 95%
Spindle cell: 88%
Embryonal: 66%
Alveolar: 54%
Undifferentiated: 40%
Which sites require LND b/c of a high propensity for LN mets? What is the risk of LN mets for these sites?
The following sites are associated with >20% LN mets rate and thus require LND:
PrT: (only if >10 yo)
Bladder: pelvic
H&N: NPX, LND typically not done for NPX
Extremities: UE (axillary) and LE (inguinal/femoral) (La TH et al., IJROBP 2011)
Which sarcoma histologies are at high risk for LN mets?
Sarcomas with significant risk of LN mets are:
Synovial cell sarcoma
Clear cell sarcoma
Angiosarcoma
RMS
Epithelioid sarcoma
(Mnemonic: SCARE)
Which International Rhabdomyosarcoma Study (IRS) called for routine LN sampling in RMS of the extremity?
IRS-IV (Neville HL et al., J Pediatr Surg 2000): 139 extremity pts, 76 pts had surgical LN evaluation; of the 10% who were clinically node positive (cN+), 50% were Pathologically node positive (pN+); of those cN0, 17% were pN+.
What are considered nonregional mets/LNs for various sites (UE, LE, pelvic organs [PrT, vagina, uterus])?
Nonregional LN stations by primary site:
UE: scalene node
Pelvic (PrT/vagina/uterus): inguinal
Retroperitoneal (RP): P-A (except if immediately adjacent)
LE: iliacs/P-A
What are the 4 favorable organ sites and their estimated 3-yr OS rate?
Favorable organ sites:
- Orbit
- Non-PM H&N
- Nonprostate/bladder GU
- Biliary
The estimated 3-yr OS is 94%.
What is the estimated 3-yr OS for RMS arising from unfavorable sites (PM H&N, prostate, bladder, extremities/trunk)?
For unfavorable sites, estimated 3-yr OS is 70%.
What are the PM H&N sites?
PM H&N sites:
Middle ear
Mastoid
Nasal cavity
NPX
Infratemporal fOssa
Pterygopalatine fOssa
PNS
Parapharyngeal space
(Mnemonic: MMNNOOPP)
What are the non-PM H&N sites?
Scalp, cheek, parotid, oral cavity, oropharynx, and larynx
