Gastrointestinal stromal tumors (GISTs) are sarcomas affecting the stomach and small intestine, with a rare subtype characterized by succinate dehydrogenase B (SDHB)-loss posing significant diagnostic and therapeutic challenges. A 62-year-old man with weight loss and abdominal pain was diagnosed with a gastric GIST showing SDHB-loss. Initial treatment with Imatinib reduced the tumor size, but surgery revealed no residual tumor. Despite adjuvant Imatinib, recurrence occurred, necessitating further surgical intervention. While GISTs typically benefit from surgery and tyrosine kinase inhibitors (TKIs), those with SDHB-loss are resistant to TKIs, requiring a different management approach. This case emphasizes the importance of surgical intervention for SDHB-deficient GISTs and the need for ongoing research into effective treatments for this subtype.

Endoscopic submucosal dissection (ESD) is considered curative for patients with early gastrointestinal cancers. However, it is a technically challenging procedure that can be time-consuming and associated with complications such as bleeding and perforation. Traction devices and techniques have been developed to mitigate these risks and reduce procedure times. Most traction devices are unavailable in New Zealand, and traction techniques have not been widely utilized due to the precision required for successful outcomes. We report the first case of traction-assisted ESD performed in New Zealand for a gastric submucosal tumor. The procedure was successfully performed using the clip with rubber band traction technique. The lesion was resected en bloc, and histology confirmed an R0, curative resection. There were no complications, and the total procedure time was 54 minutes. In conclusion, traction techniques can be effectively employed for ESD in lesions with difficult submucosal access. They contribute to safer dissections and reduced procedure times.

Background Gastrointestinal stromal tumors (GISTs) arise from Cajal\'s interstitial cell precursors and display a variety of genetic mutations, primarily in the KIT and PDGFRA genes. These mutations are linked to tumor location, prognosis, and response to treatment. This study delves into the mutational patterns of GISTs in a Mexican population and their impact on overall survival (OS) and disease-free survival (DFS). Methodology This retrospective study examined 42 GIST cases diagnosed at the Oncology Hospital of the National Medical Center XXI Century between January 2018 and December 2020. Clinical, histological, and immunohistochemical data were gathered, and mutational analysis of KIT and PDGFRA genes was conducted using second-generation sequencing. Results The study group consisted of 52.4% females and 47.6% males, with an average age of 62.6 years. The most common tumor site was the stomach (59.5%), followed by the small intestine (26.2%). KIT mutations were detected in 71.4% of cases, predominantly involving exon 11. PDGFRA mutations were observed in 7.1% of cases. Recurrence was noted in 9.5% of patients, all with high-risk tumors. No significant link was identified between specific mutations and OS or DFS. Conclusions This investigation sheds light on the genetic landscape of GISTs in the Mexican population. While no significant association was established between particular mutations and survival outcomes, the study emphasizes the importance of molecular profiling in treatment decision-making. Further studies with larger sample sizes and longer follow-up periods are necessary to validate these results and explore their clinical relevance.

Gastric schwannomas are rare types of gastrointestinal mesenchymal tumours that are slow-growing and mostly benign. They are usually asymptomatic. In some cases, nonspecific gastric symptoms, palpable mass, and bleeding can be seen. A definitive diagnosis requires pathological and immunohistochemical examination, and surgical resection offers an excellent prognosis with uncommon recurrence. We present a case of a 62-year-old woman who underwent exploratory laparotomy and wedge resection with preoperative diagnosis as gastrointestinal stromal tumor and postoperatively diagnosed as schwannoma on histopathology.

UNASSIGNED: Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the digestive tract, with surgery and tyrosine kinase inhibitor (TKI) therapy being its main treatment options. However, long-term use of TKIs may lead to drug resistance, which poses a challenge to the long-term survival of patients. We explore a new combination of transcatheter arterial chemoembolization (TACE) with TKI for liver metastasis (LM) of GIST to provide patients with more treatment options and better prognosis.
UNASSIGNED: This case report describes the application of 6 TACE sessions in the 12-year treatment of multiple LM from small intestinal stromal tumors that were resistant to multiple TKIs. The patient, a 58-year-old male, underwent multiple surgical resections and drug therapies for the LM after a primary small bowel stromal tumor had been identified and resected following an onset symptom of abdominal pain in February 2012. Despite the challenges of drug resistance and economic considerations, 6 TACE sessions effectively controlled the tumor, winning valuable treatment time for the patient. Since the initiation of ripretinib 150 mg once daily in July 2023, the tumor has continued to shrink, with satisfactory drug tolerance.
UNASSIGNED: For GIST patients with LM, TACE combined with various TKI drugs could effectively control intrahepatic tumor progression and prolong patient survival. During six TACE sessions, the patient experienced liver tumor rupture and massive bleeding. However, the bleeding was completely stopped by embolization, and the lesion shrank. Our findings provide a new perspective and treatment strategy for the treatment of LM from GIST.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal (GI) tract, typically originating from the interstitial cells of Cajal. The clinical presentations are variable according to their size and shape but rarely present as a palpable abdominal mass. Pancreatic pseudocysts are common complications of chronic pancreatitis characterized by fluid collections surrounded by a non-epithelialized wall of fibrous and granulation tissue. Patients may present with non-specific symptoms like abdominal pain, nausea, and vomiting and they generally have a history of acute pancreatitis. Small pseudocysts often resolve spontaneously, but larger ones often become symptomatic and may lead to complications. It is rare to find both a GIST of the stomach and a pseudocyst of the pancreas in the same patient. We present a unique case of a giant GIST and a pancreatic pseudocyst in a 72-year-old male who was experiencing abdominal pain and distension. Imaging revealed a massive lesion originating from the posterior gastric wall, which resembled a pseudocyst, along with a distinct cystic lesion adjacent to the pancreatic body. During surgical exploration, a complex interplay of both pathologies was discovered, requiring a comprehensive resection approach. The successful outcome highlights the importance of careful evaluation and personalized management in such rare cases.

Tissue biopsy remains the standard for diagnosing gastrointestinal stromal tumors (GISTs), although liquid biopsy is emerging as a promising alternative in oncology. In this pilot study, we advocate for droplet digital PCR (ddPCR) to diagnose GIST in tissue samples and explore its potential for early diagnosis via liquid biopsy, focusing on the PDGFRA D842V mutation and SEPT9 hypermethylated gene. We utilized ddPCR to analyze the predominant PDGFRA mutation (D842V) in surgical tissue samples from 15 GIST patients, correlating with pathologists\' diagnoses. We expanded our analysis to plasma samples to compare DNA alterations between tumor tissue and plasma, also investigating SEPT9 gene hypermethylation. We successfully detected the PDGFRA D842V mutation in GIST tissues by ddPCR. Despite various protocols to enhance mutation detection in early-stage disease, it remained challenging, likely due to the low concentration of DNA in plasma samples. Additionally, the results of Area Under the Curve (AUC) for the hypermethylated SEPT9 gene, analyzing concentration, ratio, and abundance were 0.74 (95% Confidence Interval (CI): 0.52 to 0.97), 0.77 (95% CI: 0.56 to 0.98), and 0.79 (95% CI: 0.59 to 0.99), respectively. As a rare disease, the early detection of GIST through such biomarkers is particularly crucial, offering significant potential to improve patient outcomes.

Gastric schwannomas are an exceedingly rare tumor arising from the myenteric plexus of the gastrointestinal enteric nervous system. These schwannomas are most commonly benign and reported to occur in female patients with a mean age of 58 at presentation. They are most often discovered incidentally, but can occasionally present with abdominal discomfort, obstructive symptoms, or GI bleeding. Frequently, the initial clinical consideration is for a gastrointestinal stromal tumor, which is much more common. A definitive diagnosis is made with microscopic imaging and immunohistochemical staining. Complete surgical resection, typically performed laparoscopically, is the most definitive and usually curative treatment, requiring no further follow-up. Herein, we present the first and only case of gastric schwannoma in an octogenarian and discuss an update on current diagnostic and therapeutic options.

UNASSIGNED: Imatinib mesylate (IM) is a first-line treatment option for the majority of patients diagnosed with gastrointestinal stromal tumors (GISTs). Although the clinical benefit is high, interindividual response is variable. This study thus aimed to assess how genetic polymorphisms can affect the blood levels of IM and treatment outcomes in patients with GIST.
UNASSIGNED: A total of 31 single-nucleotide polymorphisms (SNPs) in selected cytochrome P450 (P450), ATP-binding cassette transporter (ABC), solute carrier family (SLC), interleukin-4 receptor (IL4R), and vascular endothelial growth factor (VEGF) genes were genotyped using an SNP mass array platform. A total of 192 consecutive patients with GIST who received 400 mg of IM daily were enrolled into the study, with 1,485 blood samples being analyzed. According to genotypes, IM trough concentrations were tested and compared. Progression-free survival (PFS) and overall survival (OS) were also assessed.
UNASSIGNED: With a mean follow-up of 75.99 months, trough concentrations of imatinib were examined at average time points of 7.73 for each patient. Polymorphism in ABCB1 rs1045642 was found to be associated with steady-state IM trough plasma levels (P=0.008). Patients with the C genotype (CT + CC) of rs1045642 exhibited higher IM trough concentrations (1,271.09±306.69 ng/mL) compared to those with the TT genotype (1,106.60±206.05 ng/mL). No statistically significant differences in IM plasma concentration were observed for the other SNPs tested. None of the tested SNPs displayed a significant association with patients\' survival in this study.
UNASSIGNED: This is the largest cohort study evaluating the associations of SNP and imatinib blood trough levels. The ABCB1 rs1045642 genetic polymorphism may exert an effect on the pharmacokinetics of imatinib. The presence of the C allele in ABCB1 rs1045642 is predictive of a higher plasma concentration of IM.

UNASSIGNED: Gastrointestinal stromal tumor (GIST) is a rare mesenchymal tumor arising in the gut, most commonly stomach or small bowel. The most common driver mutations are KIT and PDGFRA which can be treated with imatinib or avapritinib (for PDGFRA D842V-mutant GIST), respectively. BRAF V600E mutant GISTs are rare and these do not respond to imatinib. Multiple clinical trials have shown antitumor effects with dabrafenib in BRAF-mutant melanoma and a few case reports have demonstrated treatment of BRAF V600E mutant GIST with a BRAF kinase inhibitor.
UNASSIGNED: We present a case of a 67-year-old woman diagnosed with high-risk GIST following initial resection. She was initially treated with adjuvant imatinib which was discontinued after 7 months because molecular analysis of her tumor showed the absence of KIT and PDGFRA mutations and a BRAF V600E mutation. When her disease progressed, she was started on sunitinib and subsequently regorafenib. Both agents were discontinued due to severe palmar-plantar erythrodysesthesia and clinical progression. She was subsequently started on dabrafenib based on the presence of a BRAF V600E mutation; this therapy led to a partial response. Her disease remained stable on this medication for 19 months before progression and addition of trametinib to her treatment. Her disease continued to progress and she was switched to everolimus with mixed response before re-challenging with dabrafenib and trametinib. Her imaging showed a mixed response to the re-challenge before progressing after 5 months and transitioning to hospice.
UNASSIGNED: We describe an uncommon molecular subtype of GIST with a BRAF V600E mutation. As expected, her disease was resistant to standard GIST therapy, however there was notable tumor regression following treatment with dabrafenib. This case shows the importance of molecular testing in GIST and adds to the current body of literature on the treatment of BRAF-mutant GIST.