The aim was to further characterize immunoglobulin G4-related disease (IgG4-RD) by a large-scale multicenter study of its clinical and laboratory features conducted by multidisciplinary physicians of IgG4-RD in Japan. Various specialists retrospectively evaluated IgG4-RD patients diagnosed between 1996 and 2015 in five hospitals by analyzing their baseline clinical features, laboratory, imaging, and pathological test findings, and treatment. Of the 334 patients listed, 205 were male and median age at diagnosis was 65 years. The mean number of organs involved was 3.2 at diagnosis. The most frequently affected organs were the salivary glands, followed by the lacrimal glands, lymph nodes, pancreas, retroperitoneum/periaorta, kidneys, and lungs. The mean serum level of IgG4 was 755 mg/dl, and more than 95% of patients had elevated serum IgG4 levels. The median serum level of C-reactive protein (CRP) was 0.1 mg/dl and the level was less than 1 mg/dl in 90% of patients. A total of 34.7% of patients had low serum levels of C3. Serum levels of C3 and non-IgG4 IgG, calculated as the total IgG minus IgG4, showed an inverse correlation in patients with kidney lesions, while serum IgG4 levels were not correlated with serum C3 levels. Corticosteroid was administered in 78.0% of patients, and was effective in all. The serum CRP level is generally low and the serum IgG4 level is elevated in most Japanese IgG4-RD patients, in contrast to western patients. These original findings suggest that these two parameters in IgG4-RD differ in some interesting ways from those hitherto reported in western populations. Additional studies, especially international comparative ones, are needed to elucidate the extent and significance of these differences between populations. Attention will also have to be paid to whether the existence of such differences requires consideration when devising international classification criteria.

Rheumatoid factor (RF) is the first autoantibody identified in rheumatoid arthritis (RA) which targets the fragment crystallizable (Fc) region of immunoglobulin (Ig) G. Although IgM isotype is predominant, other Ig isotypes, including IgG and IgA, also exist. While RF is not specific to RA, it remains a valuable serological test for diagnosing the disease, as evidenced by its inclusion in the 2010 classification criteria for RA based on elevated serum RF levels. RF is also associated with RA severity, including joint damage and extra-articular manifestations, serving as a poor prognostic factor and aiding in the identification of difficult-to-treat RA. Recent studies have demonstrated that high serum RF levels are associated with a reduced response to tumor necrosis factor (TNF) inhibitors. In contrast, anti-TNF antibodies lacking the Fc portion have shown stable efficacy in RA patients regardless of baseline RF levels. These findings reaffirm the clinical significance of RF measurement, 80 years after its initial discovery. This review explores the diagnostic and prognostic significance of RF and its impact on treatment selection in RA management.

Objective: This study aimed to compare drug retention rates according to the baseline neutrophil-to-lymphocyte ratio (NLR) in patients with RA initiating biologic/targeted synthetic DMARDs (b/tsDMARDs). Methods: Data were obtained from 774 treatment courses with moderate to high disease activity at the initiation of b/tsDMARD therapy from the Kansai Multicentre ANSWER cohort. Patients were categorized into NLRlow group and NLRhigh group based on the median NLR value of 3.30. A multivariate Cox proportional hazards model, adjusted for potential confounders, was used to estimate hazard ratios (HRs) for drug retention over 2 years. Results: Patients in the NLRhigh group exhibited significantly higher baseline Clinical Disease Activity Index (CDAI) scores (P = 0.004) and more frequent glucocorticoid use (P < 0.001) than those in the NLRlow group. In the NLRlow group, drug retention rates did not significantly differ among tumour necrosis factor inhibitors (TNFi), anti-IL-6 receptor antibodies (aIL-6R), cytotoxic T lymphocyte antigen 4 immunoglobulin (CTLA4-Ig) and Janus kinase inhibitors (JAKi). In contrast, within the NLRhigh group, treatment with aIL-6R and JAKi was associated with significantly higher retention rates compared with TNFi (HR = 0.53, 95% CI: 0.32–0.88; HR = 0.36, 95% CI: 0.20–0.64, respectively). At 12 months, CDAI scores did not significantly differ among the four treatment groups in either NLR group. Conclusion: In patients with elevated baseline NLR values, aIL-6R and JAKi may offer superior drug retention compared with TNFi when initiating b/tsDMARD therapy.

BACKGROUND Legionnaires' disease is one of the most common types of community-acquired pneumonia. It can cause acute kidney injury and also occasionally become severe enough to require continuous renal replacement therapy (CRRT). Non-occlusive mesenteric ischemia (NOMI) is a condition characterized by ischemia and necrosis of the intestinal tract without organic obstruction of the mesenteric vessels and is known to have a high mortality rate. CASE REPORT A 72-year-old man with fatigue and dyspnea was diagnosed with Legionnaires' disease after a positive result in the Legionella urinary antigen test pneumonia confirmed by chest radiography and computed tomography. He developed acute kidney injury, with anuria, rhabdomyolysis, septic shock, respiratory failure, and metabolic acidosis. We initiated treatment with antibiotics, catecholamines, mechanical ventilation, CRRT, steroid therapy, and endotoxin absorption therapy in the Intensive Care Unit. Despite ongoing CRRT, metabolic acidosis did not improve. The patient was unresponsive to treatment and died 5 days after admission. The autopsy revealed myoglobin nephropathy, multiple organ failure, and NOMI. CONCLUSIONS We report a fatal case of Legionnaires' disease complicated by rhabdomyolysis, acute kidney injury, myoglobin cast nephropathy, and NOMI. Legionella pneumonia complicated by acute kidney injury is associated with a high mortality rate. In the present case, this may have been further exacerbated by the complication of NOMI. In our clinical practice, CRRT is a treatment option for septic shock complicated by acute kidney injury. Thus, it is crucial to suspect the presence of NOMI when persistent metabolic acidosis is observed, despite continuous CRRT treatment.

Background: Foreign body-induced acute appendicitis is rare but could most often be caused by fish bones; those caused by endoscopic clips are highly rare. Herein, we report a case of acute appendicitis caused by endoscopic clips that developed 2 years after the endoscopic procedure. Case presentation: A 68-year-old man with a 2-year history of hemodialysis (HD) for diabetic nephropathy visited our hospital with pain in the right lower quadrant. He had undergone endoscopic submucosal dissection (ESD) for gastric adenoma 2 years earlier. Abdominal computed tomography revealed acute gangrenous appendicitis and a high-density structure lodged in the appendix. This structure was determined to be an endoscopic clip that was lodged in the patient’s appendix for 2 years. The patient underwent an emergency laparoscopic appendectomy, and an endoscopic clip covered by a fecalith was found in the appendix. Conclusion: Endoscopic clips usually fall off spontaneously in approximately a week and pass through stool. However, in this case, appendicitis developed 2 years after the ESD. An emergency surgical appendectomy may be recommended for appendicitis caused by foreign bodies. Prophylactic appendectomy or removal of foreign bodies should be considered for HD patients, even in the absence of symptoms owing to the potential severity of appendicitis in such patients.