Methods :
Three pediatric extrapulmonary spindle cell sarcomas with primitive
morphology and rhabdomyosarcomatous differentiation which raised
suspicion for association with DICER1 pathogenic variation were
studied. The cases were enrolled in the International Pleuropulmonary
Blastoma / (PPB) / DICER1 Registry. Institutional review board
approval was sought (EC/WV/TMC/41/20). Tumour sequencing was done at
Heidelberg Institute, on Illumina NextSeq platform for 130 brain tumour
related genes applying panel NPHD2015A, enriched with Agilent SureSelect
method for 1 case. This was followed by confirmation of germline
alteration using Sanger sequencing. DNA methylation profiling was also
done with Illumina Human Methylation 850 (850k) array and internal
classified V11b4 and sarcoma_v6.3. For other two cases sequencing was
performed using the Ion Torrent Personal Genome Machine (PGM) for coding
regions of DICER1 , p53 and a single amplicon of FOXL2, at
ResourcePath, through the International PPB/DICER1 Registry and
Children’s Minnesota, Minneapolis, MN.
All immunohistochemical studies on the cases were done in-house, on the
Leica Bondmax. Fluorescent in-situ hybridization (FISH) evaluation for
chromosome 8 using MYC/CEN-8 dual colour probe (Zytovision GmbH,
Germany) was performed in 2 cases.
Clinical details were retrieved from the hospital electronic medical
records.