Colonic schistosomiasis mimicking submucosal tumor

The colonoscopic features of colonic schistosomiasis are variable. Here we report a rare case of colonic schistosomiasis mimicking submucosal tumor.

A 59-year-old man was admitted to our hospital complaining of intermittent melena and thinning stool. His symptoms had lasted for 5 years. He had lived in epidemic areas and was diagnosed with colonic schistosomiasis 20 years ago because of diarrhea, but he was cured and had regular follow-up for 3 years.

The physical examination showed no positive signs such as abdominal wall varicosis and spider angioma, apart from his facial features indicating mild anemia. Laboratory data showed hemoglobin 68 g/L, stool examination was negative for ova, and there were normal levels of tumor markers such as alpha-fetoprotein, carcinoembryonic antigen and carbohydrate antigen 19 – 9. The chest radiograph was normal. Abdominal computed tomography showed mild hepatic cirrhosis. The upper-gastrointestinal endoscopy did not show varices and ulcer, but the colonoscopy revealed a submucosal tumor with congestive mucosa in the sigmoid colon ([Fig. 1 a] and [b]).

Fig. 1 a and b Colonoscopy revealed a submucosal tumor with congestive mucosa in the sigmoid colon.

Further endoscopic ultrasonography showed that the lesion originated from the submucosal layer and presented heterogeneous hypoechogenicity with multiple hyperechoic spots inside ([Fig. 2 a] and [b]).

Fig. 2 a and b Endoscopic ultrasonography showed that the lesion originated from the submucosal layer and had multiple hyperechoic spots.

The patient worried that the lesion was malignant and accepted surgery. Histopathological examination of the specimen demonstrated many calcified schistosomal ova deposited in the colonic wall, mainly in the submucosa ([Fig. 3]).

Fig. 3 Calcified schistosomal ova in the colonic wall.

Due to deposition of schistosomal ova in the submucosa producing a granulomatous reaction [1], colonoscopy in patients with schistosomiasis presents mucosal edema, hemorrhage, and ulceration at an acute stage, and a thickened bowel wall, flat or elevated nodules and polyps, or colonic stricture at a chronic stage [2]. Schistosomiasis mimicking submucosal tumor has not been reported before. Endoscopic ultrasonography (EUS) is a useful modality to diagnose submucosal tumors [3]. In this kind of case, a combination of previous history and EUS-guided fine needle aspiration (EUS-FNA) may help to make a correct judgment. Because of the potential for cancer, patients with colorectal schistosomiasis still need surveillance colonoscopy even after they have been successfully treated [4].

Endoscopy_UCTN_Code_CCL_1AD_2AJ

References

• 1 Yosry A. Schistosomiasis and neoplasia.  Contrib Microbiol. 2006;  13 81-100
• 2 Ohmae H, Sy O S, Chigusa Y, Portillo G P. Imaging diagnosis of schistosomiasis japonica – the use in Japan and application for field study in the present endemic area.  Parasitol Int. 2003;  52 385-393
• 3 Chak A. EUS in submucosal tumors.  Gastrointest Endosc. 2002;  56 S43-S48
• 4 Konishi T, Watanabe T, Shibahara J, Nagawa H. Surveillance colonoscopy should be conducted in patients with colorectal Shistosomiasis even after successful treatment of the disease.  Int J Immunopathol Pharmacol. 2006;  19 245-246