Strongyloides Stercoralis Gastric Ulcer: A Rare Cause of Upper Gastrointestinal Bleeding

Strongyloidiasis is an infection caused by Strongyloides stercoralis. Gastrointestinal manifestations typically include duodenitis, chronic enterocolitis, and malabsorption, while gastric involvement is very rare. In this case report, the ­authors present a case of upper gastrointestinal bleeding caused by a gastric ulcer with a challenging etiological diagnosis. In Portugal, there have been reports in the past century of autochthonous cases of S. stercoralis infection suggesting endemic zones, but with the current sanitation infrastructure strongyloidiasis is thought to be rare. A 56-year-old Caucasian male smoker with a history of significant weight loss presented to the emergency department with hema­temesis and abdominal pain. Upper endoscopy revealed a giant gastric ulcer with a macroscopic appearance suggestive of malignancy. Further investigation with CT scan highlighted gastric wall thickness and a spiculated lung lesion in the upper right lobe without lymph node involvement or metastatic disease. Bronchoscopy with bronchial brushing was performed. Histological examination identified squamous cell carcinoma of the lung and the patient was referred to Oncological Pneumology. Gastric ulcer biopsies ruled out malignancy and identified fragments of nematodes with inflammatory infiltrates and fibrinogranulocytic exudate, suggestive of S. stercoralis. Accordingly, the diagnosis of strongyloidiasis was made and further confirmed with molecular methods and serology. The giant gastric ulcer was affirmed to be caused by S. stercoralis infection and the patient was treated with ivermectin with improvement of epigastric pain. On reevaluation 6 weeks later the patient was asymptomatic, had gained weight, parasitological stool examinations were negative, and upper endoscopy showed complete ulcer healing. Further tests were done targeting risk factors for strongyloidiasis, and in addition to the presence of malignancy, other underlying causes for immunosuppression were ruled out. In this case report strongyloidiasis was manifested by gastric involvement with upper gastrointestinal bleeding in a patient who was subsequently diagnosed with squamous cell carcinoma of the lung.