Recurrent MYOD1 mutations in pediatric and adult sclerosing and spindle cell rhabdomyosarcomas: evidence for a common pathogenesis.
Sclerosing and spindle cell rhabdomyosarcoma (RMS) are rare types of RMS recently reclassified as a stand-alone pathologic entity, separate from embryonal RMS (ERMS). Although sclerosing and spindle cell RMS share clinical and morphologic features, a pathogenetic link based on shared molecular alterations has not been established. Spindle cell RMS in children have been associated with a less aggressive clinical course compared to adults. Recently, recurrent MYOD1 mutations were described in 44% of adult spindle cell RMS, but no pediatric tumors or sclerosing RMS were studied for comparison. Thus, we investigated 16 RMS (5 sclerosing and 11 spindle cell) in children and adults for the presence of MYOD1 mutations by targeted Polymerase Chain Reaction (PCR). Remarkably, all 5 sclerosing RMS and 4 of 11 spindle cell RMS showed the MYOD1 p.L122R hot-spot mutation. Of the five pediatric tumors, 2/2 sclerosing RMS and 2/3 spindle cell RMS showed MYOD1 mutations. Three of nine MYOD1-mutant RMS showed coexistent PIK3CA mutations, while no MDM2 amplifications were identified. All four pediatric MYOD1-mutated RMS patients died of the disease at 12-35 months following diagnosis. In conclusion, spindle cell and sclerosing RMS show recurrent MYOD1 mutations, in keeping with a single pathologic entity, regardless of age at presentation. This group however, is distinct from the infantile RMS associated with NCOA2 fusions. Although our study suggests that pediatric MYOD1-mutant RMS follow an aggressive behavior with high mortality, further studies are required to confirm this finding.
Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY.
Narasimhan P
NP
Agaram
Chun-Liang
CL
Chen
Lei
L
Zhang
Michael P
MP
LaQuaglia
Leonard
L
Wexler
Cristina R
CR
Antonescu
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D058534:Class I Phosphatidylinositol 3-Kinases; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D017570:MyoD Protein / Q000235:genetics*; D051958:Nuclear Receptor Coactivator 2 / Q000235:genetics; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics; D012208:Rhabdomyosarcoma / Q000235:genetics* / Q000473:pathology; D018233:Rhabdomyosarcoma, Embryonal / Q000235:genetics / Q000473:pathology; D012598:Sclerosis; D055815:Young Adult
D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; C498001:NCOA2 protein, human; D051958:Nuclear Receptor Coactivator 2; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human