Rhabdomyosarcomas

Question 1

Most Common Sites for Rhabdo (Descending order) “ONES”

Answer 1

Orbit (25%)
Nasopharynx
Ear (middle)/mastoid
Sinonasal cavity

Question 2

Most Common Sites for Rhabdo (Descending order) “ONES”

Answer 2

Orbit (25%)
Nasopharynx
Ear (middle)/mastoid
Sinonasal cavity

Question 3

Most common metastatic sites for rhabdomosarcoma? (3)`

Answer 3

Lungs
Bone
Bone Marrow

Question 4

Classification of Rhabdo according to site (3)

Which ones of the three are favourable vs. unfavourable?

Answer 4

1. Orbital (MC)
2. Parameningeal (NP, middle ear, sinuses, infratemporal fossa/pterygopalatine) - worse prognosis due to skullbase nearby so harder surgery
3. Non-parameningeal - easier access so amenable to surgery
   Superficial sites = Scalp, cheek, external ear
   Deep sites = larynx, parotid, oral cavity, oropharynx

Orbital + Non-Parameningeal = favourable
Non-parameningeal = unfavourable

Question 5

Histological Classification of Rhabdomyosarcoma (4)

Answer 5

1. Embryonal (Classic) - Chr 11, IGF-2 gene
2. Embryonal (Botyroid)
3. Embryonal (Spindle Cell)
4. Alveolar - poor prognosis
5. Pleomorphic/Anaplastic
6. Undifferentiated

Question 6

Most common metastatic sites for rhabdomosarcoma? (3)`

Answer 6

Lungs
Bone
Bone Marrow

Question 7

Classification of Rhabdo according to site (3)

Which ones of the three are favourable vs. unfavourable?

Answer 7

1. Orbital (MC)
2. Parameningeal (NP, middle ear, sinuses, infratemporal fossa/pterygopalatine) - worse prognosis due to skullbase nearby so harder surgery
3. Non-parameningeal - easier access so amenable to surgery
   Superficial sites = Scalp, cheek, external ear
   Deep sites = larynx, parotid, oral cavity, oropharynx

Orbital + Non-Parameningeal = favourable
Non-parameningeal = unfavourable

Question 8

Histological Classification of Rhabdomyosarcoma (4)

Answer 8

1. Embryonal (Classic) - Chr 11, IGF-2 gene
2. Embryonal (Botyroid)
3. Embryonal (Spindle Cell)
4. Alveolar - poor prognosis
5. Pleomorphic/Anaplastic
6. Undifferentiated

Question 9

Immunohistochemical Stains for Rhabdomyosarcoma (3)

Answer 9

Myogenin
Muscle Specific Actin
Desmin

Question 10

TNMStaging of Rhabdomyosarcoma

Answer 10

T staging
o	T1 – Confined to anatomic site of origin
o	T2 – Extension and/or fixation to surrounding tissue
o	A ≤5cm in diameter
o	B >5cm in diameter 
N staging
o	N0 – Not clinically involved
o	N1 – Clinically involved
o	Nx – Clinical status unknown 
M staging
o	M0 – No distant metastases 
         M1 – Distant metastasis

o I – Head and Neck (Orbit, non-PM); T1 or T2, A or B; any N; M0
o II – Parameningeal; T1 or T2, A; N0 or Nx; M0
o III – Parameningeal; T1 or T2, B; any N; M0
IV – All sites; T1 or T2, A or B; any N; M1

Question 11

Treatment of Rhabdomyosarcoma

Answer 11

1. Induction Chemo for all cases first
2. Surgery - only if 2cm margin and not recommended if cause cosmetic deformity or no increase in survival compared to ChemoRT (use in salvage therapy)
3. Radiation (40-50Gy) for post op in gross or microscopic disease
4. Do not treat neck unless Stage 2 (ie. N+)