Mucosal-associated invariant T (MAIT) cells are innate-like T cells that recognize microbial metabolites through a semi-invariant T cell receptor (TCR). Major questions remain regarding the extent of human MAIT cell functional and clonal diversity. To address these, we analyzed the single-cell transcriptome and TCR repertoire of blood and liver MAIT cells and developed functional RNA-sequencing, a method to integrate function and TCR clonotype at single-cell resolution. MAIT cell clonal diversity was comparable to conventional memory T cells, with private TCR repertoires shared across matched tissues. Baseline functional diversity was low and largely related to tissue site. MAIT cells showed stimulus-specific transcriptional responses in vitro, with cells positioned along gradients of activation. Clonal identity influenced resting and activated transcriptional profiles but intriguingly was not associated with the capacity to produce IL-17. Overall, MAIT cells show phenotypic and functional diversity according to tissue localization, stimulation environment and clonotype.

Background: The incidence of hepatocellular carcinoma (HCC) is increasing in the western world over the past decades. As liver resection (LR) represents one of the most efficient treatment options, advantages of anatomic (ALR) versus non‐anatomic liver resection (NALR) show a lack of consistent evidence. Therefore, the aim of this study was to investigate complications and survival rates after both resection types.Methods: This is a multicentre cohort study using retrospectively and prospectively collected data. We included all patients undergoing LR for HCC between 2009 and 2020 from three specialised centres in Switzerland and Germany. Complication and survival rates after ALR versus NALR were analysed using uni‐ and multivariate Cox regression models.Results: Two hundred and ninety‐eight patients were included. Median follow‐up time was 52.76 months. 164/298 patients (55%) underwent ALR. Significantly more patients with cirrhosis received NALR (n = 94/134; p < 0.001). Complications according to the Clavien Dindo classification were significantly more frequent in the NALR group (p < 0.001). Liver failure occurred in 13% after ALR versus 8% after NALR (p < 0.215). Uni‐ and multivariate cox regression models showed no significant differences between the groups for recurrence free survival (RFS) and overall survival (OS). Furthermore, cirrhosis had no significant impact on OS and RFS.Conclusion: No significant differences on RFS and OS rates could be observed. Post‐operative complications were significantly less frequent in the ALR group while liver specific complications were comparable between both groups. Subgroup analysis showed no significant influence of cirrhosis on the post‐operative outcome of these patients.

Introduction: Malignant melanoma is a neoplasia with the ability to metastasize to all organs. Most frequently, metastases derives from a skin primary. A solitary metastasis in the gallbladder is rarely mentioned in current literature. Presentation of case: We present the case of a 62-year-old female patient with the unusual metastatic spread of malignant melanoma into the gallbladder. The lesion was detected during routine follow up appointment six years after the initial surgical and radio-chemotherapeutic treatment of a malignant melanoma on the back. Following multidisciplinary team meeting, it was decided to perform a laparoscopic cholecystectomy to remove the gallbladder metastasis. Discussion: New occurrence of a melanoma metastasis in the gallbladder is extremely rare, especially in stable disease. The therapeutical concept must be discussed extensively in the present of this metastasized tumor. Conclusion: In otherwise stable disease, palliative surgery for metastasis in the gallbladder is a possible option to prevent biliary complications. In a palliative setting always weigh up the risks and benefits while maintaining the quality of life. Highlights:

Background: Focal nodular hyperplasia (FNH) is typically considered a benign tumor of the liver without malignant potential. The co-occurrence of FNH and hepatocellular carcinoma (HCC) has been reported in rare cases. In this study we sought to investigate the clonal relationship between these lesions in a patient with FNH-HCC co-occurrence. Methods: A 74-year-old female patient underwent liver tumor resection. The resected nodule was subjected to histologic analyses using hematoxylin and eosin stain and immunohistochemistry. DNA extracted from microdissected FNH and HCC regions was subjected to whole exome sequencing. Clonality analysis were performed using PyClone. Results: Histologic analysis reveals that the nodule consists of an FNH and two adjoining HCC components with distinct histopathological features. Immunophenotypic characterization and genomic analyses suggest that the FNH is clonally related to the HCC components, and is composed of multiple clones at diagnosis, that are likely to have progressed to HCC through clonal selection and/or the acquisition of additional genetic events. Conclusion: To the best of our knowledge, our work is the first study showing a clonal relationship between FNH and HCC. We show that FNH may possess the capability to undergo malignant transformation and to progress to HCC in very rare cases.

Background: 25 to 50% of patients suffering from colorectal cancer develop liver metastases. The incidence of regional lymph node (LN) metastases within the liver is up to 14%. The need for perihilar lymph node dissection (LND) is still a controversial topic in patients with colorectal liver metastases (CRLM). This study investigates the role of perihilar LND in patients with CRLM. Methods: For this retrospective study, patients undergoing surgery for CRLM at the University Hospital Basel between May 2009 and December 2021 were included. In patients with perihilar LND, LN were stained for CK22 and examined for single tumour cells (2 mm). Results: 112 patients undergoing surgery for CRLM were included. 54 patients underwent LND, 58/112 underwent liver resection only (LR). 3/54 (5.6%) showed perihilar LN metastases in preoperative imaging, and in 10/54 (18.5%), micro-metastases could be proven after CK22 staining. Overall complications were similar in both groups (LND: 46, 85.2%; LR: 48, 79.3%; p = 0.800). The rate of major complications was higher in the LND group (LND: 22, 40.7%; LR: 18, 31%, p = 0.002). Median recurrence-free survival (RFS) (LND: 10 months; LR: 15 months, p = 0.076) and overall survival (OS) were similar (LND: 49 months; LR: 60 months, p = 0.959). Conclusion: Preoperative imaging is not sensitive enough to detect perihilar LN metastases. Perihilar LND enables precise tumour staging by detecting more lymph node metastases, especially through CK22 staining. However, perihilar LND does not influence oncologic outcomes in patients with CRLM.

Objective: To evaluate the institutional learning curve of robotic liver resection (RLR), its association with surgical complexity and outcomes in an international multicenter cohort. Summary of Background Data: RLR is increasingly adopted worldwide, but the dynamics of the learning process and its impact on surgical outcomes remain poorly defined. Methods: This international, multicenter, retrospective cohort study included consecutive patients who underwent RLR between 06/2013 and 12/2024 across 22 expert centers. Based on the first 150 cases at each center, three phases were used to define the learning curve: operative time for competency, major complications for proficiency, and textbook outcome for mastery. Risk-adjusted generalized additive models were used to assess the learning process. Benchmark performance was compared to international reference values. Results: Among 2,331 patients, the most common indications were hepatocellular carcinoma (36%), benign lesions (23%) and colorectal liver metastases (21%). Operative time decreased after achieving competency (case #62), from 240 to 220 minutes ( P <0.001). Major morbidity reached a plateau during the proficiency phase (cases #63–138; 9% vs. 11%, P =0.144), while progression to mastery (cases #139–150) was associated with a higher rate of textbook outcome (76% vs. 87%, P =0.021). In contrast, conversion (5.1% vs. 4.9% vs. 2%), bile leak (4.0% vs. 5.3% vs. 3.8%), and 90-day mortality (0.7% vs. 0.9% vs. 0.9%) remained low and stable across all learning phases. Importantly, benchmark criteria for operative time, hospital stay, and textbook outcome were met across all complexity groups, including during the early learning phase. Conclusions: Robotic liver surgery shows progressive outcome improvement with early achievement of benchmark-level results and stable performance across increasing complexity. These findings indicate that, in experienced centers, RLR can be safely implemented and integrated into clinical practice, supporting its key role in modern hepatobiliary surgery.