Clinicopathological characteristics of De Garengeot hernia: six case reports and literature review

Background De Garengeot hernia, wherein the appendix is present within a femoral hernia, is a rare disease; therefore, the clinicopathological features remain to be clarified. This study aimed to reveal the clinicopathological characteristics of De Garengeot hernia. Case presentation Six patients who underwent appendectomy and herniorrhaphy between 1999 and 2018 were included. The incidence of De Garengeot hernia was 3.2% among the 182 femoral hernias that required surgery during the study period. The median age of the patients was 78 years, and five patients were women. The median body mass index was 20.1. Patients frequently had fever or elevated CRP level. Preoperative diagnoses based on computed tomography were femoral (n = 3), inguinal (n = 2), and De Garengeot (n = 1) hernias. Emergency and elective surgeries were performed in four and two patients, respectively. Histopathological examination of the resected appendix showed gangrenous appendicitis (n = 3), perforated appendicitis (n = 2), and appendiceal ischemia (n = 1) in the patients. Postoperatively, one patient developed sepsis. Conclusions Preoperative diagnosis of De Garengeot hernia is often difficult, and patients frequently have severe appendicitis. Precise diagnosis is required, and emergency surgery should be considered depending on the severity of appendicitis.


Background
De Garengeot hernia is diagnosed when the content of a femoral hernia is the appendix [1]. Preoperative diagnosis remains challenging, as it is a rare disease. In addition, surgical procedures depend on the preoperative diagnosis, severity of appendicitis, and abscess formation. There are limited reports of more than three cases of the condition collectively in a single institution [2][3][4]; therefore, the clinical characteristics and problems associated with diagnosis and treatment have not been fully clarified.

Case presentation
A review of the prospective hernia database in our department identified six cases of De Garengeot hernia (3.2%) among 182 cases of femoral hernia that required herniorrhaphy during a 20-year period between January 1999 and December 2018. Table 1 presents the background and clinicopathological factors including age, sex, body mass index (BMI), body temperature, white blood cell (WBC) count, serum C-reactive protein (CRP) level, preoperative diagnosis, surgical procedures, histopathological findings of the resected appendix, postoperative complications, and hospital stay.
Continuous variables were expressed as mean ± SD or median (IQR) as appropriate. Normality was assessed by Shapiro-Wilk test. We used JMP version 10 (SAS Open Access *Correspondence: nyuasa0257@gmail.com 1 Department of Gastrointestinal Surgery, Japanese Red Cross Nagoya First Hospital, 3-35 Michishita-cho, Nakamura-ku, Nagoya 453-8511, Japan Full list of author information is available at the end of the article Institute Inc., Cary, NC, USA) to perform statistical procedures.

Patient background
The median age of the patients was 78 years (interquartile range: IQR 70-89) and five patients were women. The median BMI was 20.1 kg/m 2 (IQR 16.4-23.6). The median body temperature was 38.0 ℃ (IQR 37.2-38.8) in four patients whose records were available. The median WBC count was 7900/μL (IQR 6400-12,000). The median CRP level was 9.7 mg/dL (IQR 5.2-18.1) in four patients whose records were available.

Preoperative diagnosis base on CT
Preoperative computed tomography (CT) was performed in all patients (Fig. 1), which revealed femoral (n = 3), inguinal (n = 2), and De Garengeot (n = 1) hernias. Retrospective review of the CT images indicated a tubular structure surrounded by or along with high/iso/low-density masses on the ventral and medial sides of the femoral vein in all patients ( Fig. 1a-f ). Figures 1f and 2 show CT images of Case 6, which could be preoperatively diagnosed as De Garengeot hernia. The axial image shows a low-density ovoid lesion with a high-density capsule and a tubular structure on the ventral and medial sides of the femoral vein, which indicates an abscess and the appendix, respectively (Fig. 1f ). On the other hand, the coronal image shows an isodense blind-ended tubular structure originating from the cecum (Fig. 2).

Surgical procedure
Emergency surgery was performed in four patients and elective surgery (within 24 h of presentation) was performed in two patients. The surgical approach was inguinal in all cases; however, an additional abdominal incision was made in two patients. Intraoperatively, an abscess was observed within the hernia sac in two patients (cases 4 and 6, Fig. 1d, f ). Appendectomy was performed in all patients. Herniorrhaphy was performed by the McVay method in five patients and the mesh plug method in one patient.

Histology of the resected appendix
Histopathological examination of the resected specimens showed gangrenous appendicitis, wherein inflammatory cells invaded the appendix with destruction of the wall architecture in three patients, perforated appendicitis in two patients, and appendiceal ischemia in one patient (Fig. 3).

Postoperative course
One patient with perforated appendicitis and diffuse peritonitis developed postoperative sepsis and disseminated intravascular coagulation (case 4). Surgical site infection (SSI) was observed in one patient (case 5), and the median length of postoperative hospital stay was 10 days (IQR 8-25), without in-hospital death.

Discussion
This study showed the clinicopathological findings of six cases of De Garengeot hernia, and revealed that the condition occurred frequently in elderly women. Furthermore, the hernia was often associated with fever and elevated CRP levels. Precise diagnosis of the condition was rare and elective surgery was performed occasionally. One-third of the patients had perforated appendicitis. Postoperative complications included SSI and sepsis, which prolonged the duration of hospital stay. The incidence of De Garengeot hernia has been reported as 0.15-5% of all femoral hernias [3,[5][6][7]. Forward movement of the appendix into the femoral canal, possibly due to the mobile cecum, the giant cecum extending into the pelvis, or increased abdominal pressure has been hypothesized as the cause of De Garengeot hernia. Obstruction of the appendiceal lumen and impaired blood circulation or venous congestion is likely to induce bacterial growth within the lumen and cause ischemic changes in the appendiceal wall. The pathological findings of the six cases in this study supported this mechanism.
Our study showed that the preoperative diagnostic rate of De Garengeot hernia was insufficient (17%, 1/6), which is in line with that reported in previous studies [8,9]. This could be due to the rarity of the disease, affecting the ability of the surgeon to interpret the CT images. However, increased diagnostic ability has been observed due to a recent surge in the recognition of cases of De Garengeot hernia by surgeons as well as advances in CT technologies, including thin-slice, coronal, and/or sagittal images. There are three key points in the CT diagnosis of De Garengeot hernia. First, a tubular structure should be identified on the ventral and medial sides of the femoral vein. Second, the tubular structure should be continuous with the bowel (cecum) in the abdominal cavity. Third, the tubular structure should have a blind end.
There is no standard approach for the treatment of De Garengeot hernia. Appendectomy and concurrent herniorrhaphy are the treatments tailored based on severity of the appendicitis, patient condition, and surgeon's preference. Mesh material has not been recommended in the presence of abscess and/or perforation, and staged surgery, laparoscopic appendectomy, or hernioplasty via the anterior approach could be an option in such cases [48,49].
Hence, Amyand hernia is defined as an inguinal hernia, containing the appendix within the hernia sac. Because De Garengeot hernia and Amyand hernia have each clinical characteristic, the clinical differences among De Garengeot hernia, femoral hernia and Amyand hernia are presented in Table 3 [50][51][52]. The incidence is comparable between De Garengeot hernia and Amyand hernia; however, the rate of appendicitis is higher in De Garengeot hernia than Amyand hernia (80% in 45 cases of our review in Japanese literature and 92.8% in 222 cases of worldwide literature review [52]). Of note, Guenther TM et al. reported that the incidence of any one of following gross appearance of the appendix including necrosis, perforation, abscess, or fistula was 42% [50]. De Garengeot hernia is female elderly predominant, while Amyand hernia is often associated with male elderly. Preoperative differential diagnosis can be made by image modality including CT: When a blind-ending tubular structure continuous with the cecum is located on the ventral and medial sides of the femoral vein within the femoral canal, the diagnosis is De Garengeot hernia. On the other hand, the tubular structure is located within the inguinal canal, the diagnosis is Amyand hernia.
Guenther TM et al. proposed a classification of De Garengeot hernia based on gross appearance of the appendix [50]. It will prompt an adequate selection of surgical procedures. However, preoperative evaluation of the severity of appendiceal inflammation is more important. If preoperative image modality indicate inflammation of the appendix, especially necrosis and perforation of the appendix, immediate surgery without using mesh such as open repair (McVay) is recommended. When image modality suggest absence of inflammation of the appendix and the patient is clinically stable, planned surgery of laparoscopic repair using mesh such as transabdominal preperitoneal approach is recommended. Cavigli et al. reported a case of De Garengeot hernia in which US showed thickened wall and hypervascularization of the appendix and hyper echoic omental fat, suggesting inflammation of the appendix without necrosis [53]. The thickness and layers of the appendiceal wall can be evaluated with US. In addition, Doppler US can reveal vascularity of the appendix. The present case reports has several limitations. First, despite recording the data of six patients with this rare disease, several clinical factors including body temperature, WBC count, and CRP levels could not be obtained due to the prolonged study duration. Second, multidetector CT was introduced in 2007 at our institution, which enabled presentation of finer images as well as coronal and sagittal images. However, three patients who were included in the early study period did not undergo this investigation. As described previously (Fig. 2), the diagnostic sensitivity can be improved by increasing the effectiveness of CT image acquisition and reconstruction [54]. Third, we retrospectively reviewed preoperative CT images; however, US images were not fully investigated due to limited experience. The advantages of US are that the technique is non-invasive and repeatable, and shows superior discriminability due to high spatial resolution. US could facilitate correct preoperative diagnosis of De Garengeot hernia and assessment of the severity of appendicitis [53,55,56].

Conclusion
De Garengeot hernia must be suspected and CT images must be carefully interpreted in patients with a groin mass and pain, as well as elevated WBC count and CRP level. De Garengeot hernia is often associated with severe acute appendicitis, and emergency surgery should be considered depending on the severity of appendicitis.