Neurofibromatosis type 1 (NF1) is an autosomal dominant disease of the skin and soft tissue. Aneurysms associated with NF1 can occur, but a secondary aneurysm rupture is very rare, with very few cases reported in literature. We describe the case of a 67-year-old female with NF1 who underwent endovascular aneurysm repair (EVAR) for an abdominal aortic aneurysm (AAA) rupture. She developed a type Ib endoleak requiring a redo-EVAR. Eighteen days after her primary operation, she was found to have two new left colic artery aneurysms. She required emergency surgery consisting of a left hemicolectomy and transverse colon colostomy. Pathology showed neurofibromatous changes to the peri-vasculature tissue, consistent with her underlying disease. Although rare, secondary aneurysms can occur following AAA repair. Patients with soft tissue connective tissue disorders, like NF1, may be at an increased risk for development of these secondary aneurysms. Endovascular repair appears to be a safe approach for NF1 patients with AAA, but endovascular management can be challenging in the setting of NF1. Surgeons should be ready to convert to open surgery if the patient displays persistent signs of bleeding or structural changes related to connective tissue disorders like NF1.

Background/Objectives: Pembrolizumab demonstrates a high response rate in patients with mismatch repair-deficient (dMMR) metastatic colorectal cancer (mCRC), with responses often sustained even after treatment cessation. However, the pathological complete response (pCR) rate in clinically responding cases remains unknown. This study aimed to evaluate the relationship between the radiological and pathological responses in patients with dMMR mCRC who responded to pembrolizumab. Methods: This retrospective study included 27 patients with dMMR mCRC treated with pembrolizumab. The radiological response was assessed using RECIST version 1.1 criteria. The pathological response was evaluated in patients who underwent metastasectomy, with pCR defined as the absence of residual cancer cells. Results: The median progression-free survival (PFS) of the cohort was 19 months. Among the 27 patients, 3 achieved clinical complete response (cCR), and 10 had clinical partial response (cPR), resulting in a response rate of 48%. All three patients with cCR maintained their responses without metastasectomy (2-year PFS: 100%). Among patients with cPR, eight maintained their responses, while two experienced progression (2-year PFS: 75%). Five patients with cPR underwent curative-intent metastasectomy, and four of them (80%) achieved pCR. Thus, at least 40% of patients with cPR in this cohort had no residual cancer histologically. Conclusions: Our findings demonstrate the significant discordance between the radiological and pathological responses to pembrolizumab in dMMR mCRC patients, with 80% of those with cPR achieving pCR upon metastasectomy. These observations highlight the need for improved response assessment methods for precision immunotherapy.

Introduction: A stoma prolapse is easy to diagnose by visual examination, and it rarely incarcerates. Therefore, manual reduction is usually performed as soon as the diagnosis is made. In this report, we describe a case of stoma prolapse that could not be reduced manually and ruptured because an incarcerated parastomal hernia occurred in the stoma, mimicking stoma prolapse. Case Presentation: A 66-year-old woman underwent total hysterectomy, bilateral salpingo-oophorectomy, pelvic and para-aortic lymphadenectomy, omentectomy, resection of dissemination, and low anterior resection with formation of a sigmoid end colostomy for endometrial cancer with infiltration of the rectum. Fourteen months after the initial operation, she presented with stoma prolapse and multiple episodes of vomiting. The prolapsed stoma was 20 cm in length, appeared swollen and edematous, and was somewhat firm. Although it looked viable, some of the mucosa was darkish red, indicating congestion. Therefore, the diagnosis was sigmoid end colostomy prolapse with an ischemic component. An attempt at manual reduction resulted in rupture, so an emergency laparotomy was performed. Intraoperatively, we found that the ileum was incarcerated in the aperture created where the colostomy had been formed. When the incarcerated ileum was released, the stoma prolapse could be reduced easily. The end colostomy was refashioned in the left upper quadrant of the abdomen. Conclusion: An incarcerated parastomal hernia can mimic stoma prolapse. If the findings differ from those of typical stoma prolapse, imaging should be performed to confirm whether another clinical entity is involved in the stoma prolapse.