Rare cause of right iliac fossa pain in a UK patient

Abstract

A 62-year-old Asian man presented with a 3-month history of right iliac fossa pain which had progressively worsened over the last 3 weeks. All blood parameters were found to be unremarkable except for mildly elevated erythrocyte sedimentation rate. CT imaging demonstrated thickening of the ascending colon and caecum. Colonoscopic biopsies showed submucosal granulomas with features suggestive of schistosomiasis and parasite serology was positive for Schistosoma antibodies. He was treated with praziquantel and showed subsequent symptomatic and radiological improvement. However, he represented nearly 2 years later and underwent a right hemicolectomy for small bowel obstruction. The resected bowel showed an inflammatory caecal mass and a terminal ileal adenocarcinoma.

Background

The human body is host to more than 350 different species of parasitic worms and protozoa with records of the most probable early human parasitic infections dating as far back as 3000 BC.¹ It is estimated that approximately 25%–30% of human population worldwide are infected with some parasitic worm species.² One of those parasites is Schistosoma which is second only to malaria in terms of worldwide prevalence.^{3 4} Schistosomiasis was first described by Theodore Bilharz in 1852 and therefore the illness is often also referred to as Bilharzia.⁵

Schistosoma is a blood fluke (trematode worm) with five main species; four of which are known to affect the gastrointestinal tract (mansoni, japonicum, mekongi, guineensis and related intercalatum) with one mainly affecting urogenital system (haematobium). It has a life cycle of trematode–vertebrate–intervertebrate with freshwater snails acting as intermediate hosts and humans as the definite hosts (figure 1). Once inside human beings, the parasite releases eggs which may get trapped in viscera leading to granulomatous reactions, fibrosis and long-term complications.

Figure 1.

Diagram showing the life cycle of Schistosoma.

Intestinal schistosomiasis is usually secondary to Schistosoma mansoni or japonicum infection but has also been reported due to S. haematobium.⁶ Intestinal involvement could lead to gastrointestinal-related symptoms such as abdominal pain, diarrhoea, dyspepsia, tenesmus, rectal passage of blood and/or mucus, and some constitutional symptoms such as fever, malnutrition, anorexia and weight loss. Intestinal involvement presenting as acute appendicitis and caecal mass have also been reported.⁴

As per the WHO, Schistosoma transmission has been reported from 78 different countries with most of the disease burden in Africa; but there are also reports from other regions including in the Middle East, South America and South East Asia.⁶ When considering western countries; it is an extremely rare disease in the USA and relatively rare in Europe with only a few hundred cases reported involving mainly immigrants, refugees and tourists.^{4 7} According to our knowledge, there are no previous published reports of intestinal manifestations of this disease in a UK patient. We present the first case report of such a patient and anticipate that there may be few more cases in the future as global travel and immigration becomes more prevalent.

Case presentation

A 62-year-old Asian man presented with a 3-month history of right iliac fossa pain which had progressively worsened over a 3-week period. He had recently started taking codeine and reported constipation but of no other gastrointestinal or constitutional symptoms.

His medical history included diverticular disease and bilateral inguinal hernia repairs. He was born in Kenya and moved to the UK approximately 45 years ago. Travel history included travelling to Kenya approximately 15 years ago and more recently Fiji, Northern and Central India in the last 2 years and a 3-week Caribbean cruise in the last 6 months.

On examination, he was normotensive and afebrile with a heart rate of 67 beats/min. Abdominal examination elicited right iliac fossa (RIF) tenderness but no mass, rigidity or rebound tenderness and Rovsing’s sign was negative.

Investigations

All blood tests were normal except for mild elevation of erythrocyte sedimentation rate. Plain abdominal X-ray showed colonic faecal loading but no evidence of bowel obstruction. CT scan showed thickening of the ascending colon and caecum with inflammatory fat stranding and adjacent reactive lymph nodes (figure 2).

Figure 2.

CT image showing caecal and ascending colonic mural thickening with pericaecal inflammatory change (arrow).

In view of the possibility of a colonic lesion, the patient underwent a colonoscopy which demonstrated minimal inflammation and mild patchy erythema of the caecum and ascending colon (figure 3). Biopsies were taken which showed submucosal granulomas with features suggestive of schistosomiasis (figure 4). Following this, he had parasite serology checked which was positive for Schistosoma antibodies. The test kit used for the serology was the DRG product S. mansoni ELISA IgG test.

Figure 3.

Endoscopy showing bowel mucosal inflammation (arrows).

Figure 4.

Submucosal granuloma with typical spine of Schistosoma organism (arrows).

Treatment

The patient’s management was discussed at the local colorectal multidisciplinary team (MDT) and he was subsequently referred to the regional Infectious Disease Unit. The patient was treated with a single treatment of praziquantel in divided doses (20 mg/kg stat dose, followed by further 20 mg/kg stat dose in 4–6 hours) and showed subsequent symptomatic and radiological improvement.

Outcome and follow-up

There was improvement in the patient’s clinical symptoms after the first dose of praziquantel and regular follow-up was advised. Approximately 11 months after initial presentation, follow-up CT showed considerable improvement although there was mild residual thickening of the caecal pole (figure 5).

Figure 5.

CT image showing improvement in colonic thickening and pericolonic inflammatory changes (arrow).

The patient however continued to report intermittent right-sided lower abdominal pain and 2 years after initial presentation presented to the emergency department with severe abdominal pain and distension. CT showed pronounced caecal and terminal ileal thickening resulting in small bowel obstruction (figure 6). The patient was placed on total parenteral nutrition and the small bowel obstruction resolved over the next few weeks. He was once again discussed in the colorectal MDT in cooperation with the regional Infectious Disease Unit. It was stated that his original single course of praziquantel had a cure rate of 85% and hence he was commenced on a further course of praziquantel with further relapse thought unlikely. Furthermore, he was investigated for tuberculosis with a QuantiFERON-TB Gold test and repeat colonoscopic biopsies which were both negative. These biopsies also showed no evidence of malignancy or active schistosomiasis. Unfortunately, the patient represented once more with subacute small bowel obstruction within a few days of discharge and after further discussion at the colorectal MDT, he underwent a right hemicolectomy. Specimen histopathology showed an inflammatory caecal mass and an adenocarcinoma of the terminal ileum just proximal to the ileocaecal valve. However, there was no evidence of active parasitic infection. The patient was referred to oncology who deemed that no adjuvant chemotherapy was needed and that the patient would be followed up with further imaging after an interval of 6 months.

Figure 6.

CT image showing caecal and distal terminal ileal mural thickening (arrow) with secondary small bowel obstruction.

Discussion

Schistosomiasis leads to significant disease burden worldwide with reported deaths due to schistosomiasis being in the region of 200 000–300 000 per annum.3 4 6 8 A relatively recent report by the WHO on the treatment of schistosomiasis showed that almost 99 million people, majority of which were from the African continent, were treated globally in 2017.⁹

Symptoms can be the result of acute, subacute or chronic infections. Acute infections can be asymptomatic or may lead to cercarial dermatitis or Katayama syndrome (systemic hypersensitivity reaction).¹⁰

As parasite eggs can potentially get trapped in any viscera, subacute and chronic infections can involve single or multiple organ systems including the gastrointestinal, genitourinary, cardiovascular, pulmonary and nervous systems (figure 1). This often leads to confusion and hence delays the diagnosis.^{4 10 11}

Gold standard test for diagnosing schistosomiasis is presence of parasite eggs in stool or urine. However, as the eggs are only produced by adult worms, which can take up to 8 weeks to develop in humans, the initial test may not be positive. This is an important consideration when investigating any patient with suspected infection. Diagnosis can also be attained by performing an endoscopic biopsy to directly visualise parasites in the tissue sample as was the case in our patient, but this more invasive approach has its potential inherent complications.^{7 8 10}

Praziquantel, a drug developed in the 1970s, is an effective and safe option which can be administered as a single or two divided oral doses producing cure rates in the range of 60%–90%.⁷ It can be repeated with efficacy of 95%–100%, approximately 6–8 weeks later as it only works on the adult worms.^{5 10}

Early diagnosis is not only important to treat the patient’s symptoms but also to prevent long-term sequelae from chronic illness which in the case of bowel could lead to iron-deficiency anaemia, ulceration, stricture, obstruction, protein-losing enteropathy, hypoalbuminaemia and rectal prolapse.^{7 8} In the colon, chronic schistosomiasis can lead to polyp formation due to granulomatous reaction at the site of inflammatory reaction.^{7 8 10}

In our patient’s case, initial CT raised the suspicion of colorectal cancer and the patient was subsequently referred to the colorectal cancer MDT. However, biopsies ruled out malignancy at that time while confirming intestinal schistosomiasis. When the patient presented with small bowel obstruction, it was thought most likely secondary to a relapse of the schistosomiasis but with neoplasia within the differential. When the patient underwent a right hemicolectomy, the resected bowel showed an inflammatory mass at the caecum but also adenocarcinoma of the terminal ileum.

The link between S. haematobium and bladder cancer has been well established in the literature.^{12 13} On the other hand, the link between intestinal schistosomiasis and colorectal adenocarcinoma is less convincing with data showing a mildly increased risk of colorectal adenocarcinoma secondary to S. japonicum and even less so with S. mansoni.^{14 15} Furthermore, there is little to no precedent in the literature of a Schistosoma-associated small bowel adenocarcinoma. In the case of our patient, we postulated that the terminal ileal adenocarcinoma was more likely secondary to the chronic inflammatory process that was a result of the parasitic infection. However, there also remains the possibility that the cancer was purely coincidental and unrelated to the previous parasitic infection.

Although this case report is the first of a patient presenting in the UK with gastrointestinal manifestations of schistosomiasis; it is intended to highlight a disease process which may become more prevalent in patients presenting across the UK due to travel to endemic areas. This may pose a diagnostic dilemma as schistosomiasis would not normally form part of the differential diagnosis in patients presenting with right iliac fossa pain and tenderness. This case highlights the need to keep an open mind and seek an appropriate travel history in all patients particularly those with unexplained RIF pain and/or tenderness.

Learning points.

• In this age of globalisation, we urge clinicians to seek appropriate travel history. Although rare, parasitic infection should be considered in the differential diagnosis of colitis with normal inflammatory markers.

• This case highlights the importance of long-term follow-up in the case of intestinal schistosomiasis given the possible long-term complications.

• When dealing with a patient with a background of chronic illness, it is important to rule out other conditions that may present in a similar way as the current presentation might be secondary to a new unrelated pathology.