Han-Ik Bae

A control group is defined as a group of people used for comparison. Depending on the type of study, it can be a group of healthy people or a group not exposed to risk factors. It is important to allow researchers to select the appropriate control participants. The Korea Biobank Project-sponsored biobanks are affiliated with the Korea Biobank Network (KBN), for which the National Biobank of Korea plays a central coordinating role among KBN biobanks. KBN organized several working groups to address new challenges and needs in biobanking. The “Normal Healthy Control Working Group” developed standardized criteria for three defined control groups, namely, normal, normal-plus, and disease-specific controls. Based on the consensus on the definition of a normal control, we applied the criteria for normal control participants to retrospective data. The main reason for exclusion from the “Normal-plus” group was blood test results beyond 5% of the reference range, including hypercholesterolemia. Subclassification of samples of normal controls by detailed criteria will help researchers select optimal normal controls for their studies.

Strongyloides stercoralis can cause systemic infection, termed strongyloidiasis, and gastrointestinal ulcer disease in immunocompromised patients. However, to our knowledge, there are no reported cases of comorbid gastric adenocarcinoma and S. stercoralis infection. Here, we report a case of an 81-year-old Korean man who presented with S. stercoralis infection coexisting with early gastric adenocarcinoma (T1aN0M0). S. stercoralis eggs, rhabditiform larvae, and adult females were observed in normal gastric and duodenal crypts. They were also observed in atypical glands representative of adenocarcinoma and adenoma. Preliminary laboratory tests revealed mild neutrophilic and eosinophilic leukocytosis. A routine stool test failed to detect rhabditiform larvae in the patient's fecal sample; however, S. stercoralis was identified by PCR amplification and 18S rRNA sequencing using genomic DNA extracted from formalin-fixed paraffin-embedded tissues. Postoperatively, the patient had a persistent fever and was treated with albendazole for 7 days, which alleviated the fever. The patient was followed-up by monitoring and laboratory testing for 4 months postoperatively, and no abnormalities were observed thus far. The fact that S. stercoralis infection may be fatal in immunocompromised patients should be kept in mind when assessing high-risk patients.