Sclerosing rhabdomyosarcoma1 (sclerosing pseudovascular rhabdomyosarcoma2)

Definition

This is a proposed rare subtype of rhabdomyosarcoma with an abundant matrix. It may represent a variant of embryonal rhabdomyosarcoma (evidenced by the presence of strap cells and the preferential expression of MyoD1 over myogenin).

Clinical features

The few cases reported occurred across a wide age range in adults and at a range of anatomical sites, including sites unusual for other types of rhabdomyosarcoma.

Macroscopic appearances

These tumours are tan to yellow, rubbery and grossly infiltrative.

Histopathology

Immunohistochemistry

 

Desmin

4/4, often limited, dot-like1, 3/32

 

Myogenin

4/4, but limited1, 2/32

MyoD1

4/4, diffuse1, 2/32, 2/32

SMA

2/4, both diffuse1, 3/3

HHF-35

2/2, variable strength1, 3/32

myf4

2/32

Vimentin

2/22

fast myosin

2/22

Myoglobin

1/12

Pancytokeratin

0/22

AE1/3

0/41

EMA

0/12

S-100

0/41, 0/22

CD31

0/22

CD34

0/22

CD99

1/41, 0/22

Collagen II

0/21

Factor VIII

0/12

NSE

0/12

   

Molecular genetics by PCR

 

Pax3/FXHR fusion gene

0/11, 0/12

 

PAX7/FXHR fusion gene

0/11, 0/12

   

Differential diagnosis

References

1Folpe, A. L., J. K. McKenney, et al. (2002). "Sclerosing rhabdomyosarcoma in adults: report of four cases of a hyalinizing, matrix-rich variant of rhabdomyosarcoma that may be confused with osteosarcoma, chondrosarcoma, or angiosarcoma." Am J Surg Pathol 26(9): 1175-83.

2Mentzel, T. and D. Katenkamp (2000). "Sclerosing, pseudovascular rhabdomyosarcoma in adults. Clinicopathological and immunohistochemical analysis of three cases." Virchows Arch 436(4): 305-11.

This page last revised 26.12.2003.

©SMUHT/PW Bishop