BACKGROUND Soft tissue tumors have various subtypes, among which sarcomas exhibit high malignant potential and poor prognosis. Malignant epithelioid tumor with GLI1 alterations was originally found in myopericytoma with t(7;12) translocation. However, recent studies indicated that it is a distinct tumor type characterized by multiple nodular distributions of oval or round epithelioid cells with a rich capillary network and a lack of specific immunophenotype. There are only a few cases reported worldwide and the optimal treatment is still being explored. CASE REPORT We report the case of a 31-year-old patient who presented with severe anemia and a large soft tissue mass in the duodenum. The patient underwent surgical resection with a negative margin, and none of the 15 lymph nodes tested positive for the tumor. Postoperative pathology and FISH testing further confirmed the presence of GLI1 disruption and S-100 and SMA negativity. Genetic testing revealed the ACTB-GLI1 fusion. No specific medication was offered after the surgery. No tumor recurrence was found during the 23-month follow-up period. The patient\'s quality of life is currently satisfactory. CONCLUSIONS Soft tissue sarcomas characterized by GLI1 gene rearrangement have a relatively less aggressive and metastatic nature, with the solid mass spreading minimally even as it grows. Patients can benefit from surgical resection, resulting in a relatively long period of tumor-free survival.

Background: Soft tissue tumors with fusions or amplifications of the GLI1 gene have distinctive molecular characteristics and have recently been considered a unique pathological entity, thus named \"GLI1-altered soft tissue tumors.\" It is a rare mesenchymal neoplasm that involves soft tissues at any site. Case presentation: We report an example of this condition in a 13-year-old Chinese male patient who presented with a mass in the tongue. The tumor was multilobulated; the tumor cells were arranged in nests and sheets, had a rich, delicate fibrovascular network, and were separated by a hyalinized fibrous stroma. The tumor cells were epithelioid to ovoid, with variable eosinophilic to pale vacuolated cytoplasm and round to oval nuclei. Immunostaining revealed that the tumor cells were positive for CDK4 and CD56. Fluorescence in situ hybridization (FISH) for GLI1 translocation was positive, with a high level of amplification of the translocated segment. Literature review: We present a comprehensive literature review of this condition, focusing on its clinical presentation, histological features, immunohistochemical profile, molecular characteristics, and prognosis.

GLI1-altered mesenchymal tumor is an emerging entity with distinctive clinicopathologic features. It shows a distinctive monomorphic round to epithelioid morphology, nested to trabecular pattern of growth, and S100+/SOX10-/SMA-immunophenotype. We report an example of this entity arising in the duodenum. A 31-year-old man presented with anemia for 1 year, a mass in the duodenal bulb was found for 9 days. Histopathologic examination revealed the tumor with distinct multilobulated architecture, a monomorphic appearance of round to epithelioid cells arranged in papillary structures, nests, cords, solid, reticular patterns, and hyalinized stroma surrounding a rich capillary network. The neoplastic cells had amphophilic to light eosinophilic or clear cytoplasm, uniform round nuclei with fine chromatin and inconspicuous nucleoli. Immunohistochemical analysis revealed strong positivity for vimentin, S100, CD56, CyclinD1, and negativity for SOX10, SMA, melan-A, HMB-45, synaptophysin, and a variety of other markers. Based on the morphology and immunophenotype, molecular studies were performed, which revealed the presence of an ACTB::GLI1 fusion transcript, confirming the diagnosis of GLI1-altered mesenchymal tumor.

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.
METHODS: 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 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.

Mesenchymal tumors harboring GLI1 gene fusions are a rare new entity that typically occur in the head and neck region of young to middle aged adults, with a particular predilection for the tongue. We report herein a case of epithelioid mesenchymal tumor with PTCH1-GLI1 gene fusion of the right submental region in an 82-year-old male never smoker. Ultrasound-guided fine needle aspiration (FNA) with concomitant core needle biopsy was performed. Cytology smears revealed a hypercellular, monotonous aspirate comprised of epithelioid to plasmacytoid cells with round regular nuclei and moderate amounts of cytoplasm. There were admixed granulomata. The patient underwent surgical resection with limited neck dissection and subsequent pathologic examination with performed next generation sequencing confirmed the presence of epithelioid mesenchymal tumor with PTCH1-GLI1 gene fusion. To our knowledge, this is the first reported example of a mesenchymal tumor harboring GLI1 gene fusion initially evaluated by FNA.

Glioma-associated oncogene homologue 1 (GLI1) is an important transcription factor downstream of Hedgehog (HH) signaling pathway, and can be used as a marker of HH signaling pathway activation. GLI1 gene translocations have been reported in several tumor types, including those associated with t(7;12) translocated dermatocytoma, plexus fibromyxoma, and gastroblastoma and other types of malignant soft tissue tumors, whereas GLI1 amplification is actually very rare in tumors. In this case report, we describe for the first time a tumor in the right mandibular gingiva, which is consistent with GLI1 amplified/fused mesenchymal tumor. The tumor cells are elliptic, polygonal and spindle tumor cells growing into nests and segments, lobulated and occasionally mitotic. The identification of these pathological features can help guide pathologists to make appropriate diagnosis and, if necessary, follow-up molecular tests. Our case has been treated with surgical resection. To date, no recurrence or metastasis has occurred and the prognosis is good.

Plexiform fibromyxoma (PFM) is a rare gastrointestinal tract tumor that develops in the stomach in most cases. Here, we report an extremely rare case of esophageal PFM. A female in her mid-30 s presented with difficulty in swallowing and breathing. Endoscopic examination revealed a submucosal tumor measuring approximately 45 × 50 mm in the upper thoracic esophagus. The biopsied specimen did not show definite histological evidence of gastrointestinal stromal tumors (GISTs). Since imatinib administration based on a clinical diagnosis of GIST did not show a therapeutic effect for tumor reduction, tumor resection was performed. The resected tumor exhibited proliferation of spindle tumor cells with abundant myxoid and vascular stroma separated by a muscular layer, indicating a plexiform arrangement. Immunohistochemical analysis demonstrated that the tumor cells diffusely expressed vimentin and alpha-smooth muscle actin, but not desmin, c-kit, DOG1, and CD34. MALAT1-GLI1 fusion was detected in formalin-fixed paraffin-embedded tissue using RT-PCR and Sanger sequencing. The results suggested that a fibromyxoid tumor can develop in the esophagus, showing an identical histology and MALAT1-GLI1 fusion to gastric PFM.

GLI1 fusions involving ACTB, MALAT1, PTCH1 and FOXO4 genes have been reported in a subset of malignant mesenchymal tumors with a characteristic nested epithelioid morphology and frequent S100 positivity. Typically, these multilobulated tumors consist of uniform epithelioid cells with bland nuclei and are organized into distinct nests and cords with conspicuously rich vasculature. We herein expand earlier findings by reporting a case of a 34-year-old female with an epithelioid mesenchymal tumor of the palate. The neoplastic cells stained positive for S100 protein and D2-40, whereas multiple other markers were negative. Genetic alterations were investigated by targeted RNA sequencing, and a PTCH1-GLI1 fusion was detected. Epithelioid mesenchymal tumors harboring a PTCH1-GLI1 fusion are vanishingly rare with only three cases reported so far. Due to the unique location in the mucosa of the soft palate adjacent to minor salivary glands, multilobulated growth, nested epithelioid morphology, focal clearing of the cytoplasm, and immunopositivity for S100 protein and D2-40, the differential diagnoses include primary salivary gland epithelial tumors, in particular myoepithelioma and myoepithelial carcinoma. Another differential diagnostic possibility is the ectomesenchymal chondromyxoid tumor. Useful diagnostic clues for tumors with a GLI1 rearrangement include a rich vascular network between the nests of neoplastic cells, tumor tissue bulging into vascular spaces, and absence of SOX10, GFAP and cytokeratin immunopositivity. Identifying areas with features of GLI1-rearranged tumors should trigger subsequent molecular confirmation. This is important for appropriate treatment measures as PTCH1-GLI1 positive mesenchymal epithelioid neoplasms have a propensity for locoregional lymph node and distant lung metastases.

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