A rare and fatal cause of right iliac fossa pain—When retroperitoneal necrotizing fasciitis masquerades as acute appendicitis: A case report and review of recent reported cases

Abstract

Introduction: Retroperitoneal necrotizing fasciitis is an uncommon, rapidly fatal condition which often mimics other diseases. Case presentation: We report a case of an elderly woman who was referred to our Emergency Department for suspected acute appendicitis. Computed tomography scan showed an iliopsoas abscess with necrotizing fasciitis on computed tomography scan. Despite aggressive surgical treatment and early antibiotics, she passed away 3 weeks later. Conclusion: Such a case has rarely been reported in an immunocompetent patient who has had no instrumentation, surgeries, or trauma. It serves to highlight the difficulty in diagnosing retroperitoneal necrotizing fasciitis, especially in the elderly patient, as well as the need to recognize it early in the Emergency Department.

Case report

A 91-year-old woman with a past medical history of hypertension and hyperlipidemia was referred by her family physician to our Emergency Department (ED) for suspected appendicitis. She complained of 1 week history of right iliac fossa pain, subjective fever, and anorexia. The pain was colicky, with no radiation, and was associated with some urinary frequency. She had been healthy prior to this episode.

At triage, she had a pulse rate of 88 beats/min, blood pressure of 98/56, and a temperature of 35.9°C. Examination of the abdomen revealed right iliac fossa tenderness together with guarding and rebound tenderness extending to the right flank and back. There were no external signs of a cutaneous infection such as warmth, erythema, crepitus, or open wounds.

Initial blood investigations revealed a raised white count of 25 × 10⁹/L (normal range, 4–10 × 10⁹ cells/L) with neutrophilia, and a C-reactive protein level of 277 mg/L (0.2–9.1 mg/L). Her lactate was elevated at 4.4 mg/dL. Microscopic urinalysis was unremarkable and an erect chest radiograph showed no free air.

A computed tomography (CT) scan of her abdomen and pelvis was ordered and revealed a large multi-loculated right iliopsoas abscess, measuring 7.0 cm by 22.0 cm by 12.5 cm, spreading in the retroperitoneal space from the hepatic flexure cranially to the femoral triangle caudally (Figures 1 and 2). It was suggested that the abscess might have originated from the sigmoid colon as there was a small extension of the abscess which effaced the fat plane of the sigmoid colon (Figure 3). The rest of the bowel including appendix were normal.

Figure 1.

CT coronal view: note the extent of the infection.

Figure 2.

Transverse view on CT.

Figure 3.

Fat plane of sigmoid effaced by abscess.

She was taken to the operating theater urgently, where copious foul-smelling pus was drained from the abscess, with extension along the fascia in between the internal oblique, external oblique, and transversalis, and also along the fascia of the psoas muscle. The bowel was noted to be clean.

The patient remained in the surgical intensive care unit where her stay was complicated by episodes of rapid atrial fibrillation and septic shock requiring inotropic support. She was empirically started on Clindamycin and Meropenem, which were then changed to Ampicillin and Sulbactam when intra-operative cultures taken showed growth of pan sensitive Enterococcus faecalis and gram positive bacillus. Blood cultures had no bacterial growth. Despite aggressive therapy and repeated debridement and vacuum-assisted closure (VAC) dressing, she developed multi-organ failure and subsequently passed away 3 weeks after admission.

Discussion

Necrotizing fasciitis (NF) is a severe infection of the soft tissue with a reported mortality rate of as high as 73%. ¹ It is rare, occurring at a rate of 0.4 cases per 1000 person-years. ² Risk factors include age, diabetes mellitus and other immunocompromised states, and illicit intravenous drug use. Urgent surgical intervention is key in the management of this condition; however, a lack of obvious cutaneous signs means diagnosis is often late rather than early. ³ Scoring systems ⁴ have been derived in an attempt to hasten the diagnosis. Sadly, NF still remains one of the most deadly surgical conditions, mainly due to the sudden onset, rapid spread, and resultant overwhelming scepticemia.^5,6 Mortality is often divided into early and late. Early deaths are usually due to sepsis and septic shock, while late deaths are often after a protracted hospital course and progressive organ failure. ⁷

The typical signs of NF such as diffuse erythema, pain out of proportion to the apparent infection, and hemorrhagic bullae are specific but, however, are only 10%–40% sensitive and occur usually in advanced disease. And, despite vital signs being stressed in critical care literature, it has been found that only half of such patients are febrile, and less than a fifth present with hypotension. ⁸

Retroperitoneal NF due to iliopsoas abscess in an immunocompetent patient is even rarer, and to our knowledge, few such cases have been published. While it has been reported to mimic acute appendicitis, necrotizing NF mainly presents with fever, abdominal pain, and peritonitis. ⁹ One case was reportedly diagnosed early with the help of periumbilical and flank erythema, which were variants of the Gray Turner’s and Cullen’s signs. ¹⁰

Based on reported literature, retroperitoneal NF has been attributed to a wide range of conditions such as pyelonephritis,^11,12 diverticulitis,^13,14 peri-anal abscess, ¹⁵ retroperitoneal stromal cell tumor, and post procedures such as hemorroidectomy, ⁹ sclerotherapy for hemorrhoids, ¹⁶ intramuscular injection of non-steroidal anti-inflammatory drugs, ¹⁷ post vaginal delivery, ¹⁸ and cesarean sections. ¹⁹ The varied presentations, etiologies, and outcomes of case reports published since 2010 are listed in Table 1.

Table 1.

Cases of retroperitoneal necrotizing fasciitis published after 2010.

References	Age, gender	Immunity status	Signs and symptoms	Length of symptoms	Etiology and/or pathogen identified	Treatment	Result
Giri et al. 9	33, M	Normal	Left loin pain, fever, vomiting, peritonitis	5 days	Trauma to the back, Escherichia coli	Surgery	Survived
Ammari 11	55, M	Not mentioned	Abdominal pain, fever, erythema, crepitus, no peritonism	Not described	Pyonephrosis, Escherichia coli	Surgery	Died
White and Fowler 20	63, F	Normal	Painful left flank nodule	3 weeks	Acute pancreatitis, Enterococcus, beta-hemolytic Streptococcus	Surgery	Survived
Ofikwu and Saeed Saqib Ramacharan 21	72, M	Diabetic	Suprapubic, LUQ pain	8 h	No source identified, Streptococcus viridans	Surgery	Died
Hyun et al. 22	72, F	Diabetic	RLQ pain	1 day	Endoscopic Retrograde Cholangio-Pancreatography (ERCP)	Surgery	Died
Atkinson 23	29, M	Not mentioned	Migratory pain to RIF Localized peritonism	1 day	Ingested toothpick causing perforation of ascending colon	Surgery	Survived
Sebastian-Valverde et al. 24	35, M	Not mentioned	Right iliac fossa pain, acute abdomen	1 day	Fournier’s gangrene, polymicrobial	Surgery	Survived
Sribatsa et al. 25	40, F	Malnourished	Generalized abdominal pain, fever, vomiting. Generalized guarding.	6 days	Right salpingo-oophoritis, polymicrobial	Surgery	Died
Hua et al. 26	50,M	Not mentioned	Right iliac fossa pain with tender mass	10 days	Ruptured appendix, polymicrobial	Surgery	Died
Hung and Yang 27	73, M	Diabetic	Right lower abdomen and right flank	Several days	Ruptured retrocecal appendix, polymicrobial	Surgery	Survived
Hung and Yang 27	91, F	Diabetic	Right flank pain	2 weeks	Ruptured retrocecal appendix	Family refused surgery	Died

M: male; F: female; LUQ: left upper quadrant; RLQ: right lower quadrant; RIF: right iliac fossa.

In our patient, no obvious source of infection was found. Although her CT scan suggested the sigmoid colon as a source of seeding, intra-operative findings did not concur, while her cultures grew gut commensals. A case series of 19 cases of NF reported a mostly mixed infection, with Bacteroides species isolated from 10 patients. ²⁸ Other associated microbes include Escherichia coli, ⁹ group A streptococcus, ²⁹ enterobacteriaceae, and Pseudomonas species. Broad spectrum antibiotics including anaerobic and gram-negative coverage must be administered early, preferably within the first 1 h after presentation. ³⁰

However, despite this knowledge, early diagnosis and prompt radical surgical intervention are the only definitive management of NF, regardless of anatomical location. Necrotic tissue is completely removed, with salvageable tissue preserved as much as possible. ³¹ Mortality rates increase when the extent of the debridement is restricted and if the initial surgery is performed more than 24 h after the onset of symptoms. Close monitoring for 24 h is crucial after the surgery, with repeat surgeries performed if clinically indicated. Wound care in the form of VAC therapy improves wound healing by absorbing exudates, reducing edema and pulling the wound edges together. ³⁰

In our patient who presented a week after onset of symptoms, this might have come too late.

Summary

Retroperitoneal NF secondary to an iliopsoas abscess in an immunocompetent patient is rare and can present atypically. A high index of suspicion is required to diagnose and initiate management. As with all cases of NF, early recognition and surgical intervention are the only definitive treatment.