Emergency imaging of a rare cause of inguinal swelling: Amyand’s hernia with perforated appendicitis and abscess–cutaneous fistula – a case report and review of the literature

Abstract

Inguinal hernias containing the appendix are rare, but even more exceptional is the occurrence of complicated appendicitis within the hernial sac with a cutaneous fistula. We report the case of a man in his 50s presenting to the emergency department with a right-sided erythematous and painful inguinal swelling secreting seropurulent material. A perforated appendix within an inguinal hernia complicated by an appendico-cutaneous fistula was diagnosed.

Background

The presence of the appendix within an inguinal hernia sac is called ‘Amyand’s hernia (AH)’. The name derives from the surgeon Claudius Amyand who, in 1735, successfully treated with appendectomy an 11-year-old boy who presented with a perforated appendix inside an inguinal hernia.¹ In literature, AH represents 0.4%–1% of inguinal hernias, and its inflammation accounts for only 0.1% of all appendicitis cases. However, perforated AH is an extremely unusual and even more rare event, described in only 0.01% of cases.^1–3

Case presentation

The patient, an otherwise healthy man in his 50s, was admitted to the emergency department complaining of a painful right inguinal swelling with a superimposed erythematous cutaneous lesion, secreting a seropurulent fluid from a small opening. The patient reported that the cutaneous lesion and the associated pain had worsened over the last 4 days. Physical examination revealed a non-reducible, painful mass in the right inguinal area, tender on palpation, discharging seropurulent material from what was suspected to be the external opening of a fistula.

Blood pressure was 130/85 mm Hg, heart rate was 80 beats per minute and body temperature was 37.8°C. Laboratory tests showed an elevated C reactive protein of 25.5 mg/dL (reference range <0.5 mg/dL) and leucocytosis with 19.2×10⁹/L neutrophils (reference range 1.5–7.7×10⁹/L). The patient denied symptoms suggestive of bowel obstruction. A right hernioplasty performed 2 years before was reported.

Investigations

A contrast-enhanced multiphase CT scan of the abdomen was performed on the same day in the emergency radiology department using a 64 detector scanner. After the first non-enhanced scan, a bolus tracking protocol was prescribed, selecting a region of interest inside the suprarenal aorta and setting a threshold of 150 Houndsfield units. Delays for the arterial and venous phases were 15 and 60 s after reaching the set threshold.

100 mL of 350 mg/mL iodinated contrast media was injected at a rate of 3 mL/s using an automated injector; a saline chaser of 40 cc followed the contrast media.

The exam showed a voluminous right inguinal hernia containing a hyperaemic, oedematous appendix with profuse periappendicular fat stranding (figure 1A–D, parasagittal and paracoronal reconstructed planes in figures 2 and 3). The appendicular walls were thickened and characterised by a vivid enhancement. No appendicoliths were identified. A periappendicular collection (figure 1C) with abundant inflammatory subcutaneous and cutaneous tissue changes was noted inside the same inguinal hernia, with a fistula extending between such collection and the cutaneous plane (figure 1D). Concurrent reactive right inguinal lymph nodes had a short axis up to 11 mm.

Figure 1.

Axial CT images, venous phase. In A–C, the appendix (red arrowhead) descends inside the right inguinal hernia. Appendiceal walls are slightly thickened and characterised by increased contrast enhancement in keeping with an inflammatory process. In C, the green arrowhead indicates a periappendicular collection inside the hernial sac: a small round formation with necrotic, non-enhancing content and thin vascularised walls. In D, blue arrowheads show small air bubbles within the subcutaneous adipose tissue surrounded by fat stranding due to oedema. The pink arrowhead points to a small solution of continuity of the cutaneous plane, consisting of the external opening of the fistula.

Figure 2.

Reconstructed CT images, venous phase. (A) Parasagittal reconstruction showing the appendix (violet in B), exiting the abdominal cavity and entering the inguinal hernial sac. Reactive fat stranding can be seen both inside the hernia (red in B) and within the subcutaneous adipose tissue (green in B), together with tiny air bubbles.

Figure 3.

Reconstructed CT images, venous phase. (A) The same findings seen in figure 2, shown from a paracoronal plane and colour-coded in B. In violet the appendix within the hernial sac, in red the periappendicular fat stranding and in green the subcutaneous oedema.

There was no ascites. Small and large bowel loops were mildly distended by gas without signs of obstruction or significant air-fluid levels. The caecum was in its normal anatomical position. Testes were within the scrotum.

A preoperative diagnosis of AH complicated by perforated appendicitis and periappendicular abscess with a cutaneous fistula was finally made by the radiologist, and urgent surgical consultation was asked.

Differential diagnosis

According to the clinical examination and laboratory findings, a complicated right inguinal hernia, a haematoma, a conglomerate of reactive lymph nodes or an infected collection were considered possible differential diagnoses.

To define whether the patient needed urgent surgical management or medical treatment, a contrast-enhanced CT was immediately prescribed shortly after the patient’s presentation.

The scan clearly showed the caecal appendix descending inside a right inguinal hernia, findings consistent with an AH.

The appendix resulted dimensionally increased because of profuse submucosal oedema and showed a diffuse hyperenhancement, consistent with an inflammatory nature; the radiologist also identified a small adjacent infected collection.

These findings, although not expected, excluded other more common causes of inguinal swelling and pain such as a complicated hernia causing intestinal obstruction (in our case the only intestinal tract within the hernial sac was the appendix itself), an abscess (on CT an inhomogeneous collection with enhancing walls), a haematoma (a hyperdense collection on the non-enhanced scan) or a conglomerate of lymph nodes.

Other intestinal complications were excluded since the scan did not show distended intestinal loops or air-fluid levels.

Treatment

In consideration of the CT findings, the patient immediately underwent emergency surgery. Perioperative antibiotics were administered according to hospital guidelines. Appendectomy and abscess drainage were performed. The inguinal hernia was treated with direct suture with no mesh due to the presence of abundant purulent material. A wound drain was placed. The postoperative course was uncomplicated. The patient received broad-spectrum antibiotics and was finally discharged 5 days after surgery.

Outcome and follow-up

After he was discharged, the patient returned as planned for a total of five surgical visits in 19 days. He was always apyretic, asymptomatic, with normal bowel motility and a normally healing surgical scar, sometimes secreting small amounts of serous liquid. No further actions were needed.

Discussion

AH is a rare cause of appendicitis, and perforated AH accounts for only 0.01% of inguinal hernias.^1–3 Fistulas between the hernial sac and cutaneous planes are reported mainly in children. The 11-year-old boy operated by Dr Amyand in 1735 had an enterocutaneous fistula originating from a perforated appendix.¹ Ruzaimie et al treated an 18-month-old baby with unrecognised AH complicated by an appendico-cutaneous fistula in total colonic Hirschsprung’s Disease.⁴ A case of AH in a 1-year-old boy presenting with chronic scrotal sinus was also described.⁵ Panagidis et al documented an AH appeared as an enterocutaneous fistula within the scrotum of a 25-day-old newborn.⁶ Finally, similar to our case, Flood et al reported the case of a woman in her mid-80s presenting with a right groin enterocutaneous fistula consistent with AH.⁷

The pathophysiology of AH is not entirely understood. It is debated whether appendicitis is the first cause or whether its herniation causes compression at the level of the deep inguinal ring facilitating blood flow alterations, bacterial overgrowth and thus inflammation.⁸ In our case, a preoperative diagnosis was made; however, this is not the rule since this condition can easily be misdiagnosed with the more frequent strangulated inguinal hernia. In fact, the most common presentation is a painful inguinal or inguinoscrotal swelling pointing towards a diagnosis of incarcerated or strangulated inguinal hernia.³ Still, symptoms vary according to the state of the appendix (normal, inflamed and perforated) and may be dull since the hernial sac limits the peritoneal spreading of infection.^{9 10} AH has been reported in any age, but it seems to be more frequent in children for the presence of patent processus vaginalis,^{11 12} while AH appendicitis is very rare in paediatric patients.¹³ It mainly affects men,¹⁴ as our patient, and it is often located on the right side in relation to the anatomical position of the appendix, although left-sided AH has been rarely described as associated with some conditions such as situs inversus, intestinal malrotation, mobile caecum or very long appendix.^15–19

In most cases, AH is a postoperative diagnosis,^20–22 since it can be misdiagnosed as incarcerated inguinal hernia, which does not require CT as part of the diagnostic workup.²³ However, a preoperative CT is valuable since it can provide information about the content of the hernial sac and, according to Laermans et al,⁸ it may be a valuable tool to make a prompt diagnosis and prevent complications.

A classification proposed in 2007 by Losanoff and Basson²⁴ identified four types of AH and their surgical treatment. Type 1 consists of an inguinal hernia containing a normal appendix, and its treatment is reduction with mesh repair. Type 2 includes acute appendicitis in inguinal hernia without abdominal sepsis. In this case, the use of a mesh is not recommended due to the elevated risk of infection, and simple primary repair is preferred. In type 3, inflammation also involves the peritoneal cavity and/or abdominal wall, and laparotomy with appendectomy and primary repair is the treatment of choice. Type 4 consists of acute appendicitis in inguinal hernia associated with another abdominal pathology, and it is managed as types 1–3 according to the inflammatory status of the appendix and with a diagnostic workup of the associated disease. According to Losanoff and Basson criteria, our patient was treated with appendectomy and direct hernioplasty without using a mesh because of the high risk of infection.

In conclusion, even if appendicitis in AH is a rare event, both clinicians and radiologists should keep a high grade of suspicion to promptly make the correct diagnosis and treat the patient accordingly.

Patient’s perspective.

At first I was scared because Emergency Room doctors were unsure about the nature of the inguinal lump I complained of. I even heard that a mass formed by lymph nodes could be the cause, and was even more frightened, not to mention the unease caused by a leaking fistula, something I never experienced.

When shortly after the CT scan the Emergency Radiologist told me it was appendicitis, albeit a rare form of it… I felt somewhat reassured.

At that point, I knew I had to undergo a surgical operation but I also hoped that it could be resolutive.

Fortunately, this was the case and since the day after surgery I’m feeling well.

Learning points.

• Amyand’s hernia (AH) is a rare event challenging to differentiate preoperatively from strangulated inguinal hernia.

• A CT scan is a precious tool to identify AH preoperatively, recognise possible complications and choose the correct workup.

• In the case of complicated AH appendicitis, a mesh implant is not recommended due to the high risk of infection.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s).