Case Report: Submucosal gastroblastoma with a novel PTCH1::GLI2 gene fusion in a 58-year-old man

Case Report: Gastric submucosal neoplasm with CTNNB1 mutation showing GLI1 overexpression and epithelial differentiation

New disease entities have been emerging based on molecular pathological findings, such as pseudoendocrine sarcoma and mesenchymal neoplasm with GLI1 gene alterations, which resemble well-differentiated neuroendocrine tumors. We report a unique case of a gastric submucosal neoplasm of approximately 1.5 cm in size with CTNNB1 mutation showing GLI1 overexpression and epithelial differentiation in a 66-year-old man. It was incidentally identified by routine health screening, and was a slowly growing tumor. Macroscopically, it was a slightly protruded tumor into the mucosa, and was primarily located from the submucosa to the muscularis propria. It was a well-defined lesion measured approximately 20 mm, and was almost stable during almost 5 years after initial identification of the tumor. Uniform round-to-epithelioid cells arranged in solid trabeculae with a microtubular/acinar appearance were seen microscopically. Occasional mitotic figures were noted, but no necrosis was observed. Immunohistochemistry (IHC) demonstrated diffuse expression of pan-cytokeratin, CD10, and CD56 without neuroendocrine markers (chromogranin A, synaptophysin, and INSM1). Molecular analysis confirmed the presence of a hot spot CTNNB1 mutation (S33C), supported by diffuse β-catenin nuclear expression by IHC. Further molecular investigations revealed the absence of GLI1 gene rearrangements, GLI1 amplification, and other fusions. Several differential diagnoses were considered; however, none adequately fit the criteria. The patient remained disease-free for 24 months postoperatively without further adjuvant therapy.

Expanding the Spectrum of GLI1-rearranged Neoplasms of the Gastrointestinal Tract to Include Monophasic Keratin-positive Epithelial Neoplasms

GLI1-altered tumors form a diverse group occurring in various anatomic locations. In the alimentary tract, the most established are gastroblastoma, a biphasic epithelial-mesenchymal neoplasm of the stomach, and plexiform fibromyxoma, a pure spindle cell neoplasm. The spectrum of GLI1-rearranged gastrointestinal tumors has recently expanded with reports of cases in other parts of the GI tract, some exhibiting gastroblastoma-like features and others being pure mesenchymal neoplasms. These tumors often display a nonspecific immunophenotype, with only CD56 and cyclin D1 expression being common. Biphasic GLI1-altered tumors show diffuse keratin positivity in the epithelial component only, and GLI1-altered mesenchymal tumors typically lack or show only focal keratin expression. This study details 2 GLI1-rearranged gastrointestinal tract tumors with diffuse keratin and CD56 expression, composed entirely of epithelial cells with a nested growth pattern and finely stippled monotonous nuclei, leading to an initial suspicion of neuroendocrine tumor in both cases, despite lack of synaptophysin and chromogranin expression. Diffuse strong nuclear cyclin D1 expression was seen in both cases, and conversely, strong cyclin D1 staining was only seen in 5.4% (4/74) of well-differentiated neuroendocrine tumors tested. These 2 GI tract neoplasms highlight a widened spectrum of GLI1-rearranged tumors, now including monophasic epithelial neoplasms with diffuse keratin expression.

Gastroblastoma - a case report and literature review

OBJECTIVE

To report a new case of gastroblastoma and conduct an exhaustive review of the clinical, morphological, immunohistochemical, molecular features, diagnosis, treatment, and prognosis, to enhance understanding of this condition.

METHODS

We retrospectively analyzed the case of a 50-year-old woman diagnosed with gastroblastoma and conducted a review and summary of relevant literature.

RESULTS

To date, 27 cases have been reported, including the present case. The mean patient age at the time of presentation was 35.0 years (range, 5-74 years), and the disease showed no sex predilection. The most common location was the gastric antrum, and the average lesions size was 5.7 cm (range, 1.3-15 cm). Most patients underwent gastrectomy(n = 23), while several underwent ESD(n = 2) or EFTR(n = 1). Fusion genes were identified, including MALAT1-GLI1(n = 8), EWSR1-CTBP1(n = 1), PTCH1:GLI2(n = 1), and ACTB-GLI1(n = 1)Four patients had metastasis and one of them dead of disease. Immunohistochemical (IHC) analysis revealed that pancytokeratin was always positive in epithelioid components, while vimentin and CD10 were always positive in mesenchymal components. CD56 were often positive in both two components.

CONCLUSION

A comprehensive evaluation of clinical and pathological features is crucial for accurate diagnosis. Partial gastrectomy and EFTR could be an appropriate treatment. The risk factors that affect the prognosis need more cases to be clearly defined. We present this exhaustive literature review to increase awareness of gastroblastoma, better characterize the disease, and provide a reference point for gastroblastoma research in the future.

Gastroblastoma with a novel ACTB::GLI1 gene fusion in a 19-year-old male

Gastroblastoma is a rare gastric biphasic tumor composed of mesenchymal and epithelial elements in variable proportions. These tumors usually arise in the gastric antrum of children and young adults and are reported to harbor a recurrent MALAT1::GLI1 fusion. Herein we report a case of gastroblastoma in a 19-year-old male who presented with intermittent epigastric abdominal discomfort. Antrectomy revealed a 5.6-cm multi-lobulated, tan-pink mass with solid and focally cystic areas involving the submucosa, muscularis propria, and subserosa. All tumor cells demonstrated immunoreactivity for GLI-1, CD56, and vimentin; epithelial elements expressed pancytokeratins (AE1/AE3 and Oscar), and mesenchymal cells demonstrated focal positivity for CD10. Next generation sequencing revealed a novel ACTB::GLI1 fusion without evidence of the recurrent MALAT1::GLI1 fusion. Nine months after surgery, the patient is well without evidence of recurrence or metastases. To our knowledge, this is the first case of gastroblastoma harboring this novel ACTB::GLI1 fusion.

Blastomas of the digestive system in adults: A review

Blastomas, characterized by a mixture of mesenchymal, epithelial, and undifferentiated blastematous components, are rare malignant neoplasms originating from precursor blast cells. This review focuses on digestive system blastomas in adult patients, including gastroblastoma, hepatoblastoma, and pancreatoblastoma. Gastroblastoma is a biphasic, epitheliomesenchymal tumor, with only sixteen cases reported to date. In addition to the characteristic histology, metastasis-associated lung adenocarcinoma transcript 1 - glioma-associated oncogene homolog 1 gene fusion is typical, although recently novel ewing sarcoma breakpoint region 1 - c-terminal binding protein 1 and patched 1 - glioma-associated oncogene homolog 2 fusions have been described. Hepatoblastoma is exceptionally rare in adults and can show a variety of histologic patterns which may cause diagnostic difficulty. Pancreatoblastoma, primarily a pediatric tumor, displays acinar differentiation and squamoid nests with other lines of differentiation also present, especially neuroendocrine. Diagnostic approaches for these blastomas include a combination of imaging modalities, histopathological examination, and molecular profiling. The treatment generally involves surgical resection, which may be supplemented by chemotherapy or radiotherapy in some cases. Prognoses vary with gastroblastoma generally showing favorable outcomes post-surgery whereas hepatoblastoma and pancreatoblastoma often have poorer outcomes, particularly in the setting of metastases. This review highlights the complexity of diagnosing and managing these rare adult blastomas as well as the need for ongoing research to better understand their pathogenesis and improve treatment strategies.

Gastroblastoma: a case report and literature review

Objective

Gastroblastoma is an extremely rare gastric tumor. Its pathogenesis remains unclear and there is a lack of specific clinical symptoms. The aim of this paper is to report a case of gastroblastoma and provide references for the diagnosis, treatment, and prognosis of this disease.

Methods

The diagnosis and treatment of a 51-year-old female patient with gastroblastoma were retrospectively reported. Analyzing this case by combining the clinical data such as imaging and pathological results of patients with the relevant literature.

Results

The patient's chief complaint was the presence of melena persisted for over two weeks. Abdominal contrast-enhanced CT showed gastric antral nodules, and micro-probe endoscopic ultrasonography was considered as "gastric antral protruding lesions". The initial diagnosis of "gastric stromal tumor" was made after admission, and surgical treatment was performed on September 23, 2021. Postoperative pathology showed that gastric mixed epithelial and stromal tumor, combined with immunohistochemical staining, was suggestive of gastroblastoma. No signs of tumor recurrence or metastasis were observed during the 2-year follow-up.

Conclusion

Combined with the existing literature reports, the incidence of gastroblastoma is mainly higher in young men, and the predilection site is gastric antrum. The biological behavior of the tumor tends to be indolent, and the prognosis of most cases is favorable. However, due to the extremely small number of cases, this conclusion still needs a large number of cases and follow-up data to support. Postoperative pathological and immunohistochemical examination results are the only methods for definite diagnosis at present, and surgery is the first choice for treatment.

MALAT1 functions as a transcriptional promoter of MALAT1::GLI1 fusion for truncated GLI1 protein expression in cancer

BACKGROUND

The long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a cancer biomarker. Furthermore, fusion of the MALAT1 gene with glioma-associated oncogene 1 (GLI1) is a diagnostic marker of plexiform fibromyxoma and gastroblastoma; however, the function of this fusion gene remains unexplored.

METHOD

In this study, we elucidate the structure and function of the MALAT1::GLI1 fusion gene. To this end, we determined a transcriptional start site (TSS) and promoter region for truncated GLI1 expression using rapid amplification of the 5' cDNA end and a luciferase reporter assay in cultured cells transfected with a plasmid harboring the MALAT1::GLI1 fusion gene.

RESULTS

We found that the TATA box, ETS1 motif, and TSS were located in MALAT1 and that MALAT1 exhibited transcriptional activity and induced expression of GLI1 from the MALAT1::GLI1 fusion gene. Truncated GLI1, lacking SUMOylation and SUFU binding sites and located in the nucleus, upregulated mRNA expression of GLI1 target genes in the hedgehog signaling pathway.

CONCLUSIONS

We demonstrate a distinct and alternative function of MALAT1 as a transcriptional promoter for expression of the MALAT1::GLI1 fusion gene. Our findings will aid future research on MALAT1 and its fusion gene partners.

Gastroblastoma mimics the embryonic mesenchyme of the foregut: a case report

BACKGROUND

Gastroblastoma is a rare gastric tumor composed of epithelial and spindle cell components. The characteristic MALAT-GLI1 fusion gene has only been identified in 5 reported cases. We report the morphological characterization of gastroblastoma with the MALAT1-GLI1 fusion gene in a young Japanese woman.

CASE PRESENTATION

A 29-year-old Japanese woman visited Iwate Medical University Hospital with upper abdominal pain. Computed tomography revealed a tumor in expansive lesions involving the gastric antrum. Histologically, we observed a biphasic morphology composed of epithelial and spindle cell components. The epithelial components appeared as slit-like glandular structures with tubular or rosette-like differentiation. The spindle cell components consisted of short spindle-shaped oval cells. Immunohistochemical (IHC) analysis revealed that the spindle cell component was positive for vimentin, CD10, CD56, GLI1, and HDAC2, and focally positive for PD-L1. The epithelial component was positive for CK AE1/AE3, CAM5.2, and CK7, and negative for CK20 and EMA. Both components were negative for KIT, CD34, DOG1, SMA, desmin, S100 protein, chromogranin A, synaptophysin, CDX2, and SS18-SSX. The MALAT-GLI1 fusion gene was detected molecularly.

CONCLUSIONS

We report the following new findings with this case: (i) gastric tumors mimic the gastrointestinal mesenchyme in the embryonic period; (ii) nuclear expression of PD-L1 and HDAC2 were observed in the spindle cell component of a gastroblastoma. We speculate that histone deacetylase (HDAC) inhibitors may offer a promising treatment option for gastroblastoma.

Gastroblastoma Treated by Endoscopic Submucosal Excavation with a Novel PTCH1::GLI2 Fusion: A Rare Case Report and Literature Review

Gastroblastoma is an extremely rare stomach tumor that primarily presents in adolescent and early adulthood, with a biphasic cell morphology of epithelioid and spindle cells. In light of its similarity to other childhood blastomas, it has been named gastroblastoma. Few patients showed a potential of metastasis and recurrence, however, most of the reported cases were alive, with no evidence of the disease after surgical treatment. Commonly, MALAT1-GLI1 fusion has been considered to be the most relevant mutation. Herein, we present a case of an asymptomatic 58-year-old man who happened to find a submucosal gastric mass during a gastroscope and received endoscopic submucosal excavation (ESE). He turned out to have a gastroblastoma with a novel PTCH1::GLI2 fusion confirmed by Sanger sequencing. The patient was discharged two days after ESE without any complication and was recurrence-free during his one-year follow-up. According to the previous literature and our own experience, in cases with characteristic histopathology and immunohistochemistry patterns, a diagnosis of gastroblastoma should be considered even without a MALAT1-GLI1 fusion. Gastroblastoma pursues a favorable clinical outcome and endoscopic therapy could be an effective alternative treatment choice.