Pediatric mesenchymal tumors harboring variant NTRK fusions (ETV6-negative) are being increasingly described; however, the histologic and clinical features of these variant NTRK tumors and their relationship to classic infantile fibrosarcoma are not well characterized.
Molecular biology has been valuable in showing dermatofibrosarcoma protuberans and infantile fibrosarcoma that are characterized by COL1A1-PDGFB and ETV6-NTRK3 rearrangements respectively.
The ETV6-NTRK3 (EN) fusion has been implicated in various cancers, including infantile fibrosarcoma, secretory breast carcinoma, and acute myeloblastic leukemia, and has exhibited in vivo and in vitro transforming ability.
We developed a next-generation sequencing-based assay designated ChildSeq-RNA that uses the Ion Torrent platform to screen for EWSR1-FLI1 and EWSR1-ERG, PAX3-FOXO1 and PAX7-FOXO1, EWSR1-WT1, and ETV6-NTRK3 fusions of Ewing sarcoma (ES), alveolar rhabdomyosarcoma, desmoplastic small round cell tumor, and congenital fibrosarcoma, respectively.
Polymerase chain reaction study for ETS Translocation Variant 6/neurotrophic tyrosine kinase receptor, type 3 fusion transcript was positive, and the diagnosis of infantile fibrosarcoma was established.
Infantile fibrosarcoma (IFS) is a malignant neoplasm, arising in children younger than 2 years of age and with a hallmark chromosomal translocation t(12;15)(p13;q26) encoding an ETV6-NTRK3 fusion oncoprotein.
Remarkably, this entity is the only epithelial tumor of the breast with a balanced translocation, t(12;15), that creates an ETV6-NTRK3 gene fusion encoding chimeric tyrosine kinase also encountered in cellular mesoblastic nephroma and infantile fibrosarcoma.
Remarkably, this entity is the only epithelial tumor of the breast with a balanced translocation, t(12;15), that creates an ETV6-NTRK3 gene fusion encoding chimeric tyrosine kinase also encountered in cellular mesoblastic nephroma and infantile fibrosarcoma.
In two exceptional instances, the same translocation and gene fusion occurs in two unrelated diseases: ETV6-NTRK fusion in infantile fibrosarcoma and secretory carcinoma of the breast, and ALK-TPM3 fusion in inflammatory myofibroblastic tumor and large cell anaplastic lymphoma.
The ETV6-NTRK3 (TEL-TRKC) gene fusion was discovered by breakpoint analysis of the t(12;15)(p13;q25) translocation associated with congenital fibrosarcoma, a pediatric soft tissue malignancy.
The ETV6-NTRK3 (TEL-TRKC) gene fusion was discovered by breakpoint analysis of the t(12;15)(p13;q25) translocation associated with congenital fibrosarcoma, a pediatric soft tissue malignancy.
The cellular variant of congenital mesoblastic nephroma (but not the classic variant) has been shown to bear the same t(12;15)(p13;q25) and ETV6-NTRK3 gene fusion as infantile fibrosarcoma, a tumor with which it shares morphologic and clinical features.
The cellular variant of congenital mesoblastic nephroma (but not the classic variant) has been shown to bear the same t(12;15)(p13;q25) and ETV6-NTRK3 gene fusion as infantile fibrosarcoma, a tumor with which it shares morphologic and clinical features.
Furthermore, several Tel-TrkC transcripts encoding for kinase isoforms of the Tel-TrkC protein were detected in congenital fibrosarcoma and may be involved in oncogenesis.
Congenital-infantile fibrosarcoma. A clinicopathologic study of 10 cases and molecular detection of the ETV6-NTRK3 fusion transcripts using paraffin-embedded tissues.