A Case of NTRK Fusion Corpus Sarcoma With Pseudobiphasic Growth Pattern and Literature Review.

The incidence of neurotrophic tyrosine kinase receptor ( NTRK ) fusion uterine sarcoma is extremely low, and reports have been mostly focused on cases localized to the cervix. So far, only 4 cases have been reported of the uterine corpus. In this study, we reported a case of NTRK fusion corpus sarcoma. This study aimed to expand the morphologic spectrum of this tumor, which showed adenosarcoma-like features not previously described. The tumor was confined to the uterine corpus, polypoid growth, comprised predominantly of a fascicular proliferation of spindle cells, entrapping benign endometrial glands, and exhibited a pseudo-biphasic growth pattern. The tumor showed coexpression of S-100, CD34, and pan-Trk by immunohistochemistry, DNA-sequencing identified TPR-NTRK1 gene fusion and AKT1(E17K) mutation. Four cases of NTRK fusion corpus sarcoma were reviewed. The clinicopathologic features, immunohistochemical phenotype, molecular testing, and prognosis of 5 cases including this one were summarized and analyzed. Most cases exhibited an infiltrative growth pattern and showed mild or moderate cytologic atypia. The potential for these tumors to be misclassified as uterine adenosarcoma or other uterine mesenchymal tumors. The diagnosis relies on pan-Trk, S-100, CD34 immunohistochemistry, and molecular testing. Surgical resection is the mainstay of treatment for most patients. Distinguishing these tumors from morphologic mimics is significant because patients with advanced-stage disease may be treated with TRK inhibitors.