Author: Julie Anne G. Calusim
Date of Acceptance: 5 November 2024
Summary
Neglected tropical diseases (NTDs) such as schistosomiasis (SCH) are diseases of poverty commonly found in tropical and subtropical regions. [1] NTDs are included as targets for global action in the United Nations Sustainable Development Goal 3.3, which aims “to end epidemics caused by NTDs” by 2030 to “ensure healthy lives and promote well-being for all at all ages”. [2]
Schistosomiasis (SCH) is a chronic infection caused by trematodes, which develop in the human host after exposure to fresh water snail larvae. Schistosomiasis affects 200 million people globally and is endemic to 70 countries, where it accounts for approximately 300,000 to 500,000 deaths annually. [3] In 2017, approximately 143 million people were infected with SCH. [4]
In the Philippines, S.japonicum affects approximately 12 million people, with 2.5 million directly exposed to the infection. [5] Schistosomiasis remains a public health problem in endemic areas like in the Philippines with approximately 12 million people residing in 28 endemic provinces located across 12 different geographical zones. A total of 190 municipalities and 1212 barangays (villages) are currently endemic, based on surveys conducted over the past decade. [6] Treatment of uncomplicated schistosomiasis is accomplished with a single 40-60 mg/kg dose of Praziquantel, an anthelmintic drug, however, pathology related to egg deposition may require surgical intervention. [7] Intestinal involvement of schistosomiasis uncommonly involves the formation of non-obstructive polypoid lesions; however, obstructing fibrotic stenosis and strictures secondary to chronic infection are extremely rare with only nine reported cases in the literature. [3]
In this case report we present a rare case of complete large bowel obstruction secondary to severe intestinal schistosomiasis that mimics a colonic mass. In its rarity, there were only nine reported cases in the world literature.
Case presentation
Investigations
A 30-year-old, female, born in Southern Leyte Philippines, currently residing in Naic, Cavite, presented at the ER with a chief complaint of abdominal distension. History of present illness revealed three months history of intermittent right lower quadrant pain, with associated decreased in stool caliber, weight loss and abdominal distension.
Patient had several consults to different clinics. Laboratory tests such as urinalysis, fecalysis, CBC, and abdominal UTZ were done which revealed normal results. One month PTC, patient noted increased in severity of symptoms this time with associated vomiting and constipation. Patient had another consult at a different clinic, was given pain meds and unrecalled antibiotics, and was sent home.
Interim, persistence of symptoms and absence of flatus and bowel movement for three days prompted consult at our emergency department (ED). On physical examination, the patient was noted to have a blood pressure of 100/60mmHg, tachycardic at HR 112bpm, tachypneic at RR 25cpm, and febrile with a temperature of 37.9C, with an O2Sat of 98%. The patient was also noted to be pale.
Examination of the abdomen revealed the following findings; a midline infra-umbilical scar was noted, abdomen is distended, with noted guarding and direct and rebound tenderness in all quadrants, tympanitic on percussion. Digital rectal examination was done which revealed absence of mass, good sphincter tone, empty and collapsed rectal vault, with noted tinged of black tarry stool per examining finger. Computed BMI is 13.
Past medical history revealed Pulmonary Tuberculosis (post-treatment for 6 months) and one LTCS last 2013. Patient denies smoking and alcohol intake. Family history revealed liver cirrhosis in the paternal side. Patient denies any history malignancy in the family. A chest and abdominal film done previously from another institution was handed over by the patient showing distended bowel loops with multiple air-fluid levels, and paucity of pre-sacral gas, consistent with complete gut obstruction.
Patient was then placed on NPO, hydrated, NGT was inserted revealing an initial output of 500 cc of fecaloid material. Indwelling foley catheter was also inserted with noted concentrated but adequate urine output 1cc/kg/hr. Patient was prepared for surgery, and consent was secured from the patient and relative. The initial surgical plan for the patient is Emergency Exploratory Laparotomy. Initial impression that time was Complete Gut Obstruction prov sec to Post-operative Adhesions vs. Gastro-intestinal Tuberculosis TB.
Differential diagnosis
Colorectal cancer, gastrointestinal tuberculosis.
Treatment
The patient underwent Exploratory Laparotomy with an intra-operative findings of edematous, dilated, friable but viable large bowel loops. An ileocecal mass approx. 5.0 x 5.0 cm in its widest diameter, with enlarged palpable nodules were noted at the bowel segment. The liver, spleen, and the rest of the organs are grossly normal, no palpable lymph nodes noted. Cut section of the mass revealed, stricture and fibrosis at the affected bowel segment, causing complete obstruction of the lumen. Since an ileocecal mass was noted intra-operatively, a consideration of possible malignancy was also entertained. With these findings, an R0 resection was planned since the mass is resectable. The resident surgeons with the guidance of the consultant in charge decided to do Right Hemicolectomy with Double Barrel Ileocolostostomy. Anastomosis was not done in this case due the condition of the bowel segments which are noted to be edematous and friable.
Outcome and follow-up
Post-operatively, the patient recovered well from surgery and was discharged seven days post-op. The patient had two follow-up consults at the OPD and on the second consult, the biopsy result of the specimen came out with the following findings: Acute and chronic inflammation with abscess formation involving full thickness of intestinal wall, Schistosomiasis, non-specific reactive hyperplasia pericolic lymph nodes, viable margins of resection.
With these findings, the patients was reported to the infectious disease specialist in our institution, where the patient and her family were advised regarding the transmission and need for treatment. All family members received Praziquantel treatment, and have their stools tested for the presence of Schistosomal eggs. Two months after the operation, the patient came at the OPD for another follow-up, with negative Katokatz result, suggesting the absence of Schistosomal infection.
Discussion
Schistosomiasis inducing obstruction with stenosis is exceedingly rare even in endemic regions. It involves the formation of non-obstructive polypoid lesions through the deposition of schistosomal eggs in the superficial layers of the submucosa that progresses to build-up of reactive cellular debris and inflammatory granulation tissue. [8]
The manifestations of acute schistosomiasis intestinal infection are intestinal mucosal hyperemia, edema, and punctate hemorrhages. Microscopic examination reveals numerous neutrophils and eosinophil deposits. Chronic infection manifests as intestinal wall vascular network disorder, smooth or prominent mucous membrane yellow-white or grayish-yellow nodules, colonic polyps and intestinal lumen stenosis. The yellow nodules are mostly the presentations of calcified worm egg deposition, fibrous tissue thickening and atrophy of the overlying mucosa. [8]
At least five trematode species are known to infect humans: S. haematobium, S. intercalatum, S. japonicum, S. mansoni, S. mekongi. The schistosome life cycle occurs in two hosts: snails and mammals. Either asexual or sexual reproduction occurs, depending on the type of host. Dam and irrigation are potential sites for outbreaks of schistosomiasis. Movements of populations with schistosomiasis for example from rural to urban areas, can cause the spread of schistosomiasis. [9] Two major species of schistosomes commonly produce gastrointestinal disease: S.mansoni and S.japonicum.
In endemic areas, the infection is usually acquired in childhood. The prevalence and intensity of infection rises with age and peaks at approx. 15-20 years. Only 5-10% of patients with schistosomiasis will be heavily infected, and the remainder will have mild to moderate disease. [10]
Schistosomiasis usually presents with non-specific and may mimic other GI problems such as, non-specific abdominal pain, diarrhea, constipation, rectal bleeding, obstruction, intussusception, ischemic colitis. [10] The most striking histopathologic feature is the development of granulomas, well-defined clusters of inflammatory cells embedded in a collagen-rich ECM, around mature parasite eggs deposited in target organs. The granuloma response is responsible for the pathogenesis of the disease, causing severe inflammation, tissue eosinophilia, collagen deposition, fibrosis and portal hypertension. Therefore, much of the symptomatology of schistosomiasis is associated with egg-induced granulomatous inflammatory response and fibrosis. [11]
In endemic regions, the mainstay of diagnosis and identification of species relies on evidence of parasitic eggs in the stool. [3] Schistosomiasis can also be diagnosed through finding parasitic eggs in tissue biopsies of concerning lesions attained through endoscopy, but often is limited by variance in egg shedding. [3] Anti-schistosomal antibodies can be detected using serologic testing but cannot differentiate between active or previous infection.
Additionally, immunoassays are expensive and potentially are limited to specific Schistosoma species. [3] Radiologically, the use of abdominal x-rays and barium enemas can be effective in focally identifying polyps or strictures. Despite being easily accessible and low-cost, these modalities suffer from poor sensitivity and specificity. [3] The sensitivity does improve by using higher fidelity imaging tools such as CT scans. [3]
Given the rare presentation of partial colonic obstruction due to fibrotic inflammation, there are no clear guidelines regarding treatment recommendations. Usually, management of intestinal schistosomiasis involves a single oral dose of 40-60 mg/kg of praziquantel, a safe and effective drug that achieves cure rates between 70-90%. [3] Management has been based on expert opinion and published case reports, where resection is used to definitely treat the intestinal manifestations and confirm diagnosis thru pathological analysis. [3]
Given the inability to distinguish between Schistosoma and malignancy, and the inherent underlying risk of future malignancy, surgical resection remains the treatment of choice, as employed in our patient
Learning points / take home messages
Schistosomiasis mimicking colonic mass, causing complete gut obstruction is extremely rare even in endemic areas in the world. Pre-operative diagnosis may also be difficult since most cases are asymptomatic, while others presents with non-specific symptoms. In low resource area, differentiating Schistosoma-induced colonic fibrosis vs colonic mass might be difficult. Surgery and Praziquantel may be the most effective modality for patients with colonic mass secondary to schistosomiasis.
References
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