Seung-Myoung Son

Rationale: We present the case of gallbladder adenomyomatosis (GA)-induced cholecystogastric fistula (CGF) that mimicked an invasive gastric gastrointestinal stromal tumor (GIST), leading to diagnostic and surgical challenges in an emergency setting. Patient concerns: A 71-year-old woman presented to the emergency department with acute abdominal pain and clinical signs of mechanical small-bowel obstruction (SBO). Diagnoses: Contrast-enhanced abdominal computed tomography (CT) revealed a 6-cm mass along the gastric antrum with apparent hepatic invasion and concurrent features of SBO. The gallbladder was not visualized. Esophagogastroduodenoscopy (EGD) demonstrated a subepithelial tumor-like bulge with a small mucosal opening in the gastric antrum, raising suspicion of a fistulous tract. Interventions: Emergency exploratory laparotomy identified two phytobezoars in the small bowel, which were treated by segmental resection and primary anastomosis. The gastric mass was found to be densely adherent to the liver, and bile leakage was encountered during dissection, prompting intraoperative hepatobiliary consultation. Outcomes: Histopathological examination of the resected specimen confirmed GA with inflammatory granulation tissue at the gallbladder–gastric serosal interface, with no evidence of malignancy. The patient recovered uneventfully and was discharged 29 days postoperatively. Lessons: This case highlights a novel and clinically significant diagnostic pitfall: GA-induced CGF can convincingly simulate an invasive gastric neoplasm on multimodal imaging and endoscopy. Recognition of biliary red flags, including non-visualization of the gallbladder on CT, a mucosal opening adjacent to a subepithelial-appearing lesion on EGD, and intramural cystic foci on imaging, is essential for accurate preoperative diagnosis.

Rationale: Primary gastric plasmacytoma is a rare form of extramedullary plasmacytoma that may mimic gastric adenocarcinoma or lymphoma. Although it is generally considered a localized disease, delayed histologic remission after radiotherapy and subsequent systemic progression remain poorly characterized. Patient concerns: A 75-year-old man was referred after screening endoscopy revealed an approximately 3-cm protruding gastric mass initially suspected to represent advanced gastric cancer. Diagnoses: Repeat biopsy demonstrated atypical plasmacytoid cell proliferation with CD138 positivity and kappa light-chain restriction. Comprehensive systemic evaluation, including bone marrow biopsy, serum and urine electrophoresis, immunofixation, serum free light-chain analysis, and PET/CT, revealed no evidence of systemic disease, supporting a diagnosis of primary gastric plasmacytoma. Interventions: Definitive radiotherapy was delivered to the stomach at a total dose of 45 Gy in 25 fractions. Outcomes: Follow-up endoscopy at approximately 3 months demonstrated marked regression of the lesion; however, biopsy revealed residual monoclonal plasma cells with persistent kappa light-chain restriction. Repeat biopsy performed approximately 9 months after radiotherapy demonstrated loss of light-chain restriction with a polytypic kappa/lambda pattern, consistent with histologic remission. During subsequent follow-up, multifocal osteolytic skeletal lesions developed, and biopsy of the L5 vertebral lesion confirmed plasma cell neoplasm. Following multidisciplinary reassessment, the patient was ultimately managed as non-secretory multiple myeloma, and systemic therapy with bortezomib, lenalidomide, and dexamethasone (VRd) was initiated. Lessons: This case demonstrates that histologic remission after radiotherapy may be delayed and that, although uncommon, systemic progression may occur despite the absence of systemic disease at initial staging. Long-term surveillance integrating clinical, radiologic, and pathologic findings is therefore essential, and early post-treatment biopsy findings should be interpreted in the context of the overall clinical course.

Rationale: Pneumopericardium is a rare clinical finding in cancer patients and is typically associated with direct tumor invasion or postoperative complications, particularly in intrathoracic malignancies, such as lung or esophageal cancer. Patient concerns: Herein, we report the case of a 58-year-old man with advanced gastroesophageal junction adenocarcinoma who developed pneumopericardium and pericarditis in the absence of tumor invasion. Diagnoses: The condition was presumed to result from the radial force exerted by a self-expandable metal stent placed for palliation of dysphagia. Computed tomography revealed the presence of air within the pericardial sac and a direct communication with the stent, without radiological evidence of tumor invasion into the pericardium. Interventions: Given the terminal nature of the disease and lack of response to palliative systemic therapy, the patient was managed conservatively. Outcomes: The patient succumbed to his illness 1.5 months later. Lessons: To the best of our knowledge, this is the 1st reported case of pneumopericardium induced by the radial force of a self-expandable metal stent in a patient with gastroesophageal junction adenocarcinoma, highlighting the importance of clinical vigilance for pneumopericardium, even in the absence of classic risk factors. Early recognition may guide appropriate management and inform prognostic discussions in patients receiving palliative care.

Mixed neuroendocrine non-neuroendocrine neoplasms of the gastrointestinal tract are rare, with only a few cases documented in the literature. In particular, there are no reports of a rectal mixed neuroendocrine non-neuroendocrine neoplasm with regional lymph node metastasis of the neuroendocrine tumor component. Here, we present the case of a man in his early 70s with an incidental finding of multiple colonic polyps during a routine colonoscopy, including a 0.9-cm sessile polyp in the rectum. Repeat colonoscopy was performed for endoscopic mucosal resection. Histopathological examination revealed a biphasic tumor comprising a well-differentiated adenocarcinoma and a grade 1 neuroendocrine tumor, leading to a diagnosis of rectal mixed neuroendocrine non-neuroendocrine neoplasm. Because the adenocarcinoma component had invaded the submucosa and involved the resection margin, an ultralow anterior resection was performed. Notably, postoperative pathological analysis revealed metastasis of the neuroendocrine tumor component to a regional lymph node, an unusual finding not previously reported in the literature. Despite this, the patient remained recurrence-free for 2 years without adjuvant therapy. To the best of our knowledge, this is the first such case to be reported in the literature. Given the limited understanding of mixed neuroendocrine non-neuroendocrine neoplasms, particularly cases with low-grade neuroendocrine components, further case accumulation is necessary to develop standardized treatment guidelines.

Rationale: Esophageal and head and neck cancers often coexist due to field cancerization, which causes multiple squamous cell carcinomas (SCCs) in the upper aerodigestive tract. However, guidelines for the differential diagnosis and optimal treatment of synchronous esophageal and head and neck SCC are lacking. This study highlights the diagnostic and therapeutic challenges of these coexisting malignancies. Patient concerns: A 52-year-old man presenting with dysphagia was diagnosed with esophageal SCC, and an incidental retropharyngeal tumorous lesion was found during staging. Diagnoses: Biopsy revealed SCC in both lesions. To differentiate between metastatic disease and a second primary SCC, immunohistochemistry (IHC) and next-generation sequencing (NGS) were performed. The retropharyngeal SCC showed strong p16 staining, indicating human papilloma virus (HPV)-related origin, while the esophageal SCC was p16-negative. NGS revealed distinct genetic profiles for each lesion, confirming synchronous double primary SCCs. Interventions: The patient underwent definitive concurrent chemoradiotherapy for both SCCs. Outcomes: The patient achieved a complete response for both lesions and remains recurrence-free 1 year after treatment. Lessons: This case underscores the importance of HPV testing and/or NGS in patients with multiple SCCs in the upper aerodigestive tract to accurately differentiate primary cancers from metastases.

Background and Objectives: Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is involved in pancreatic cancer progression and is an attractive therapeutic target for pancreatic cancer. In this study, we evaluated the therapeutic efficacy of small-interfering RNA (siRNA) targeting CEACAM6 (siCEACAM6) and the CEACAM6-suppressive microRNA-29a (miR-29a) in a pancreatic ductal adenocarcinoma xenograft mouse model using pH-low insertion peptide (pHLIP) technology, which targets the acidic tumor microenvironment. Materials and Methods: The delivery vectors for siRNA and miRNA were constructed by conjugating the peptide nucleic acid forms of siCEACAM6 and miR-29a to a peptide with a pHLIP, enabling the transport of siRNA and miRNA across the plasma membrane. The tumor-suppressive effects of pHLIP-siCEACAM6 and pHLIP-miR-29a were assessed in vivo using a BALB/c xenograft mouse model with the injection of the CFPAC-1 human pancreatic ductal adenocarcinoma cell line. Results: The treatment of CFPAC-1 cells with pHLIP-siCEACAM6 and pHLIP-miR-29a under acidic pH conditions suppressed CEACAM6 expression and decreased cell viability. In a xenograft mouse model, the intravenous injection of pHLIP-siCEACAM6 and pHLIP-miR-29a suppressed tumor growth by up to 25.1% (p < 0.01) and 21.2% (p < 0.01), respectively, compared to the control mice treated with pHLIP-scr. Conclusions: Our results demonstrated the efficacy of the pHLIP-mediated delivery of siCEACAM6 and miR-29a as a promising therapeutic strategy in a pancreatic ductal adenocarcinoma xenograft mouse model. The pHLIP technology, which targets the acidic tumor microenvironment, represents an innovative approach to the delivery of small RNAs to pancreatic ductal adenocarcinoma cells, providing new potential strategies for pancreatic cancer treatment.

Kim H, et al. J Gastric Cancer. 2025 Oct;25:e46. https://doi.org/10.5230/jgc.2025.25.e46

Son SM, et al. J Gastric Cancer. 2024 Dec;25:e2. https://doi.org/10.5230/jgc.2025.25.e2

Rationale: Duodenal mucosa-associated lymphoid tissue (MALT) lymphoma is a rare condition. Simultaneous presence of pancreatic ductal adenocarcinoma along with duodenal MALT lymphoma has not been documented in the scientific literature. We report an exceptionally rare case of synchronous duodenal MALT lymphoma and pancreatic ductal adenocarcinoma. Patient concerns: A 75-year-old man was referred to our hospital with dyspepsia and weight loss. Diagnoses: Esophagogastroduodenoscopy was performed, revealing synchronous tumor comprising pancreatic ductal adenocarcinoma and MALT lymphoma of the duodenum. Interventions: Given that the pancreatic carcinoma would be the primary determinant of prognosis, we prioritized treatment of the pancreatic carcinoma. Consequently, we performed a Whipple operation first. Post-operative pathologic examination revealed metastasis of pancreatic cancer to peri-pancreatic lymph nodes, whereas the MALT lymphoma was localized to the duodenum; therefore, only adjuvant chemotherapy for pancreatic cancer was performed. Outcomes: To date, the patient has had no recurrence of either the pancreatic cancer or the MALT lymphoma. Lessons: To the best of our knowledge, this is the first case to be reported. Awareness of this co-occurrence may help diagnosis and management of similar cases.

Adenoid cystic carcinoma (ACC) rarely occurs in the nasolacrimal duct (NLD), and when it does, it has nonspecific manifestations. To the best of our knowledge, one case of ACC in the NLD has been reported in the literature. Herein, we report a second case of ACC in the left NLD, concerning a man in his late 60s. He presented with epiphora, and swelling and pain below the left medial canthus. Nasal endoscopy revealed bulging of the lateral wall in the left nasal cavity, with an intact nasal mucosa. Paranasal sinus computed tomography showed an enhancing mass at the epicenter of the left NLD, involving the maxillary sinus, inferior turbinate, and nasal cavity, with bony destruction. The patient underwent superomedial maxillectomy. The pathology was high-grade ACC. Despite undergoing five rounds of postoperative radiotherapy, the ACC recurred 11 months after the operation. Early identification is critical for reducing the morbidity and mortality of patients with ACC in the NLD.