坂本 博次

INTRODUCTION: Follicular lymphoma is an indolent B-cell lymphoma that can involve the gastrointestinal tract, most commonly the small intestine. Although rituximab-based therapy is effective, transformation to diffuse large B-cell lymphoma (DLBCL) can occur and becomes difficult to diagnose after CD20 loss. CASE PRESENTATION: We report the case of a 64-year-old woman initially diagnosed with primary small intestinal follicular lymphoma who subsequently developed transformation to DLBCL 2 years after rituximab therapy. Double-balloon enteroscopy revealed progression of mucosal lesions, raising suspicion of histologic transformation. However, endoscopic biopsy was inconclusive because of the loss of CD20 expression, likely resulting from prior rituximab therapy. Surgical resection was performed to relieve intestinal obstruction and to establish a definitive diagnosis. Histopathological examination confirmed transformation to CD20-negative DLBCL. CONCLUSION: This case highlights the diagnostic limitation of endoscopic biopsy following rituximab therapy. Therefore, clinicians should be cautious in relying solely on endoscopic findings and remain open to surgical intervention to achieve a timely and accurate diagnosis.

We herein report a kidney transplant recipient with recurrent bleeding due to multiple ileal ulcerations associated with mycophenolate mofetil (MMF). Symptoms persisted despite surgical resection and embolization. Double-balloon enteroscopy revealed multiple ulcerations, and a biopsy helped exclude other causes. The discontinuation of MMF led to rapid symptom resolution and healing of the ulceration. Intestinal complications after renal transplantation vary, and MMF-induced enteritis, although rare, should be considered. This case highlights the diagnostic value of enteroscopy in identifying drug-induced small intestinal injuries and underscores the importance of including MMF in the differential diagnosis of post-transplant gastrointestinal bleeding.

BACKGROUND: Peutz-Jeghers syndrome (PJS), a rare genetic disorder characterized by hamartomatous gastrointestinal polyps, poses increased risks of various cancers. Despite the importance of early intervention, the optimal timing for jejunal-ileal polypectomy remains unclear owing to the limited number of comparative studies. METHODS: Herein, we conducted a nationwide survey in Japan and analyzed data from 184 patients with PJS identified through a two-stage sampling process. The initial screening of 2912 medical institutions yielded 1748 facilities, of which 1077 responded to the survey. Time-dependent Cox proportional hazards models and logistic regression analyses were used to examine the association between the timing of jejunal-ileal polypectomy and the risk of surgery for intussusception. RESULTS: Among 184 patients (47.0% women; mean age, 33.5 years), intussusception was the most common complication (67.7%). In the Cox proportional hazards analysis excluding surgeries within 1 year of diagnosis, early jejunal-ileal polypectomy was associated with a reduced risk of surgery for intussusception (adjusted hazard ratio, 0.17; 95% confidence interval [CI] 0.04-0.74, p = 0.018). Logistic regression analysis showed higher odds of surgery in the late treatment group compared with the early treatment group (adjusted odds ratio, 4.26; 95% CI 1.38-13.16, p = 0.012). CONCLUSIONS: Early jejunal-ileal polypectomy may reduce the risk of intussusception in patients with PJS. However, the need for frequent endoscopic procedures must be balanced considering patient burden. These findings support the importance of early intervention and highlight the need for optimized surveillance strategies that consider clinical effectiveness and patients' quality of life.