ETV6::NTRK3 Fusion-Positive Wild-Type Gastrointestinal Stromal Tumor (GIST) with Abundant Lymphoid Infiltration (TILs and Tertiary Lymphoid Structures): A Report on a New Case with Therapeutic Implications and a Literature Review.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract, with proto-oncogene, receptor tyrosine kinase (c-kit), or PDGFRα mutations detected in around 85% of cases. GISTs without c-kit or platelet-derived growth factor receptor alpha (PDGFRα) mutations are considered wild-type (WT), and their diverse molecular alterations and biological behaviors remain uncertain. They are usually not sensitive to tyrosine kinase inhibitors (TKIs). Recently, some molecular alterations, including neurotrophic tyrosine receptor kinase (NTRK) fusions, have been reported in very few cases of WT GISTs. This novel finding opens the window for the use of tropomyosin receptor kinase (TRK) inhibitor therapy in these subtypes of GIST. Herein, we report a new case of NTRK-fused WT high-risk GIST in a female patient with a large pelvic mass (large dimension of 20 cm). The tumor was removed, and the histopathology displayed spindle-predominant morphology with focal epithelioid areas, myxoid stromal tissue, and notable lymphoid infiltration with tertiary lymphoid structures. Ten mitoses were quantified in 50 high-power fields without nuclear pleomorphism. DOG1 showed strong and diffuse positivity, and CD117 showed moderate positivity. Succinate dehydrogenase subunit B (SDHB) was retained, Pan-TRK was focal positive (nuclear pattern), and the proliferation index Ki-67 was 7%. Next-generation sequencing (NGS) detected an ETV6::NTRK3 fusion, and this finding was confirmed by fluorescence in situ hybridization (FISH), which showed NTRK3 rearrangement. In addition, an RB1 mutation was found by NGS. The follow-up CT scan revealed peritoneal nodules suggestive of peritoneal dissemination, and Entrectinib (a TRK inhibitor) was administered. After 3 months of follow-up, a new CT scan showed a complete response. Based on our results and the cases from the literature, GISTs with NTRK fusions are very uncommon so far; hence, further screening studies, including more WT GIST cases, may increase the possibility of finding additional cases. The present case may offer new insights into the potential introduction of TRK inhibitors as treatments for GISTs with NTRK fusions. Additionally, the presence of abundant lymphoid infiltration in the present case may prompt further research into immunotherapy as a possible additional therapeutic option.

Clinicopathological analysis of 18 cases of secretory carcinoma of the salivary glands.

Background/purpose: Secretory carcinoma (SC) is a rare salivary gland tumor that featured by ETV6::NTRK3 gene fusion, and was included in the WHO Classification of Head and Neck Tumors since 2017. Nevertheless, the description of SCs by WHO is still vague. This study examined 18 SC cases by using both histomorphology and molecular pathology for diagnostic determination, especially immunohistochemical features of SCs. Materials and methods: Based on WHO characteristics, 18 patients with SC admitted between 2001 and 2022 were included in this study. Main histomorphological patterns, FISH analyses of the ETV6::NTRK3 gene fusion, and immunohistochemical analyses of S100, mammaglobin, DOG1, ADFP, CA6 and Ki-67 were performed. Results: Among the 18 SC patients, the median age of onset was 39.22 years. Grossly, the average tumor size in 2.96 cm with various texture from soft to tough. The majority patients were positive for S100, mammaglobin, and negative for DOG1, except for one patient negative for S100 (Case 18). All patients were positive for ADFP, and the majority patients were negative for CA6, except for Case 9. Two cases were found recurrence, and the tumor were found both in parotid gland with local invasion. Conclusion: Combined with the results of previous studies, we proposed that the combination of all five markers, S100, mammaglobin, DOG1, ADFP and CA6, could contribute more to differential diagnosis of SCs with other salivary carcinomas, especially with AciCC. The prognosis of SCs is optimistic in most cases, but larger patient cohort and long-term follow-up are still needed.

Therapeutic targeting of RBPJ, an upstream regulator of ETV6 gene, abrogates ETV6-NTRK3 fusion gene transformations in glioblastoma.

Fusion genes are abnormal genes resulting from chromosomal translocation, insertion, deletion, inversion, etc. ETV6, a rather promiscuous partner forms fusions with several other genes, most commonly, the NTRK3 gene. This fusion leads to the formation of a constitutively activated tyrosine kinase which activates the Ras-Raf-MEK and PI3K/AKT/MAPK pathways, leading the cells through cycles of uncontrolled division and ultimately resulting in cancer. Targeted therapies against this ETV6-NTRK3 fusion protein are much needed. Therefore, to find a targeted approach, a transcription factor RBPJ regulating the ETV6 gene was established and since the ETV6-NTRK3 fusion gene is downstream of the ETV6 promoter/enhancer, this fusion protein is also regulated. The regulation of the ETV6 gene via RBPJ was validated by ChIP analysis in human glioblastoma (GBM) cell lines and patient tissue samples. This study was further followed by the identification of an inhibitor, Furamidine, against transcription factor RBPJ. It was found to be binding with the DNA binding domain of RBPJ with antitumorigenic properties and minimal organ toxicity. Hence, a new target RBPJ, regulating the production of ETV6 and ETV6-NTRK3 fusion protein was found along with a potent RBPJ inhibitor Furamidine.

The Giant Infantile Fibrosarcoma of Fetal Oropharynx and Anterior Neck.

Introduction: Infantile fibrosarcoma (IFS) usually arises in the extremities during the first 12 months of life and responds well to surgery. It is unusual in the oropharynx or the prenatal period. Case report: A giant solid mass was first detected in the oropharynx and anterior neck at 24 weeks of gestation by ultrasound and fetal MRI. An EXIT procedure with intrapartum intubation with appropriate supportive therapy was successful. The diagnosis of IFS was made postpartum, and the lesion responded to neoadjuvant chemotherapy. Conclusion: IFS may arise as early as 24 weeks of gestation. In this case, an EXIT procedure allowed postpartum diagnosis with subsequent treatment.

Fetal Mediastinal Fibrosarcoma. Report of Two Cases.

Introduction: One-third of fetal soft tissue tumors are malignant and include congenital fibrosarcoma (CF). We report two fetal CFs arising in the posterior mediastinum. Case Presentation: In case 1, the CF resulted in a mediastinal shift, extensive infiltration of the tumor around adjacent structures, pulmonary hypoplasia, pleural effusion, and rapid growth. The pregnancy was terminated. Case 2 had multiple intrathoracic masses, thoracic hypoplasia, pleural effusion, and fetal death. Both were diagnosed as fibrosarcoma at fetopsy. Discussion: Although congenital CF tends to be locally aggressive with a low metastatic rate, it tends to grow rapidly and the tumor location can affect fetal survival. In Case 1, the tumor demonstrated locally aggressive behavior whereas multiple distant metastases such as lung, liver, adrenals, and left eye were detected in Case 2. The tumor was directly responsible for intrauterine fetal demise in the second case.

Clinical value of marker genes in the diagnosis of salivary gland mammary secretory carcinoma / 中华内分泌外科杂志

Objective:To investigate the clinicopathological features, immunophenotype, diagnosis and differential diagnosis of mammary analogue secretary carcinoma of salivary gland (MASC) .Methods:From Jan. 2018 to Jan. 2021, 28 cases of salivary gland MASC were collected in Ningbo Diagnostic Pathology Center, and 10 cases of acinar cell carcinoma and 10 cases of adenoid cystic carcinoma were selected as controls. Immunohistochemical envision method was used to detect the expression of S-100,, DOG-1, CD117, SOX-10, Mammaglobin and Vimentin, and fluorescence in situ hybridization was used to detect the fusion gene of ETV6-NTRK3.Results:The S-100 protein, SOX-10 and Vimentin of MASC of salivary gland were diffusingly positive (28/28) , Mammaglobin (22/28) and CD117 (19/28) were partially positive, and DOG-1 was negative. ETV6-NTRK3 fusion transcription was successfully detected in 26 of 28 salivary gland MASC cases, of which 23 were positive and 3 were negative.Conclusions:Salivary gland MASC is a low-grade malignant epithelium tumor. Comprehensive detection of the expression levels of S-100 protein, SOX-10, DOG-1, Mammaglobin and CD117 is of great value for the diagnosis and differential diagnosis of MASC. FISH detection of ETV6-NTRK3 gene fusion has important reference value for definite diagnosis.

Secretory carcinoma of the skin with lymph node metastases and recurrence in both lungs: A case report.

Secretory carcinoma of the skin is an extremely rare adnexal tumor, histopathologically identical to homologous lesions in the salivary glands and breast tissue. Although this tumor was previously reported as indolent, we report a case of secretory carcinoma of the skin with metastases and recurrence. The patient, a 31-year-old women, had a subcutaneous mass in the right axilla. The resected specimen contained a circumscribed mass, with proliferating tumor cells that exhibited prominent nucleoli. They exhibited glandular and papillary growth patterns and there were amphophilic secretions in the glands. Immunohistochemically, the tumor cells were positive for mammaglobin and S100. The tumor was surrounded by sweat glands and there was no mammary glandular tissue, suggesting that it was derived from axillary sweat glands. Accordingly, we made a diagnosis of secretory carcinoma of the skin. Four years after the operation, there were metastases in both lungs. The resected specimen revealed a tumor identical to that of the original skin tumor. Next-generation sequencing-based multiplex gene assay performed on the metastatic tissue revealed an ETV6-NTRK3 fusion gene. This is a rare case report of secretory carcinoma of the skin with lymph node metastases and recurrence in both lungs.

Mammary analogue secretory carcinoma: An Indian experience of a novel entity.

AIMS: To explore clinical, histopathological and immunohistochemistry (IHC) features of mammary analogue secretory carcinoma (MASC) with systematic literature review. SETTINGS AND DESIGN: Hospital based cross-sectional study. SUBJECTS AND METHODS: The data of all cases of MASC diagnosed over a period of 1 year i.e., from July 2017 to July 2018 were retrieved. The haematoxylin and eosin (H and E) sections, and IHC sections were studied. A strict histological and recently updated criteria were applied and patients with a confirmed diagnosis of MASC were included in the study. A systematic literature review was conducted by searching the PubMed and National Centre for Biotechnology Information database. STATISTICAL ANALYSIS USED: Microsoft Excel 2010. RESULTS: The present case series is 27th in the English literature and 1stcase series describing its histopathology in the Indian literature. The mean age of presentation is 43 years. Female preponderance was found i.e., M:F ratio of 0.5. CONCLUSION: Histopathology and if necessary, followed by IHC is required for the confirmation of diagnosis of MASC. We should be aware about this recently described entity which is usually mistaken for other low grade salivary gland carcinomas like Acinic cell carcinoma (AciCC) and Mucoepidermoid carcinoma (MEC). The knowledge about its typical morphology, high degree of suspicion and IHC confirmation with both S-100 and Mammaglobin help in precise diagnosis.