Alveolar Rhabdomyosarcoma (ARMS)

OVERVIEW

Alveolar rhabdomyosarcomas (ARMS) account for 20% of all pediatric rhabdomyosarcoma, occurring less frequently than embryonal rhabdomyosarcoma (ERMS). 

There are two recurrent translocations observed in this tumour type. 60% of cases will have a t(2;13)(p36;q14) resulting in the fusion of the 5’PAX3 and the 3’FOXO1, 20% will have a t(1;13)(p36;q14) resulting in the fusion of the 5’PAX7 and the 3’FOXO1, and 20% of tumours will have neither of these translocations.  In patients presenting with metastatic disease the overall survival was lowest in patients with a PAX3-FOXO1 rearranged tumour.

TEST REQUIREMENTS

  • Completed CGL Cytogenetics Solid Tumour Testing requisition form
  • FFPE Tumour specimen (see Specimen Guidelines, Cytogenetics FISH FFPE test type)
    • An H&E stained slide with the tumour region circled, and the estimated % tumour content written in the Tumour Content field of the requisition.  NOTE: A minimum of 10% tumour and at least 200 nuclei is required.
    • Specimen block and/or at least one unstained slide for each probe requested.

TURN-AROUND TIME

Results are reported within fourteen days from receipt of specimen and completed requisition form.  

RESULTS REPORTING

  • This FISH assay is performed to aid in the diagnosis of ARMS with up to 80% of ARMS harbouring either a PAX3-FOXO1 or a PAX7-FOXO1 rearrangement.
  • A negative FISH result neither confirms nor excludes the diagnosis of ARMS.
  • Specimens are reported as Positive for a PAX3/7-FOXO1 rearrangement or Negative for a PAX3/7-FOXO1 rearrangement.

METHOD

FISH analysis is performed on the provided paraffin embedded tissue using two “in house” dual colour, dual fusion translocation probes. One localizes to PAX3 (RP11-109L24 OR RP11-161I23) and FOXO1 (RP11-89L15 AND RP11-213E4), and the other to PAX7 (RP11-164D21 AND RP11-412G9) and FOXO1.

REFERENCES

  1. Skapek et al Pediatr Blood Cancer (2013) PMID: 23526739.
  2. Sumegi et al Genes Chromosomes Cancer  (2010) PMID: 19953635
  3. Nishio Lab Invest  (2006)  PMID: 16607381