despite the advances in hygiene processes , approximately 30 - 100 million people in tropical and subtropical regions are infected with strongyloides stercoralis . s. stercoralis is well known to be able to induce systemic infection ( strongyloidiasis ) and/or gastrointestinal ulcer disease in immunocompromised patients , which could further increase patient mortality . however , to the best of our knowledge , there are no reported cases of comorbid gastric adenocarcinoma and s. stercoralis infection . here , we present a case of gastric adenocarcinoma comorbid with s. stercoralis infection in an elderly man with a long history of diabetes mellitus . an 81-year - old korean man presented with weight loss , poor oral intake , and abdominal discomfort for 3 months in november 2013 . although the patient had hypertension and diabetes mellitus for several years and had been treated with standard medication , he was relatively healthy until recently . physical examination showed no signs of fever , chills , diarrhea , abnormal bowel movement or sound , or skin rash . furthermore , the patient did not report any previous intake of alcohol , tobacco , herb mediation , or inhaled corticosteroids . in addition , he had no significant family history or recent history of travel to tropical or subtropical regions . esophagogastroduodenoscopy revealed chronic atrophic gastritis with intestinal metaplasia and multiple erosions in the stomach ; in particular , an ulcerative lesion , suggestive of type iic early gastric cancer , was observed in the anterior wall of the antrum , and an atrophic lesion was observed in the duodenum ( fig . microscopic examination of a biopsy specimen from the gastric mass in the antrum revealed a well - differentiated adenocarcinoma as well as parasite eggs , rhabditiform larvae , and adult worms presumably of s. stercoralis in normal gastric pits . 2a ) ; however , some parasite eggs and adult worms were observed along with scattered eosinophils in the mucosa of normal duodenal pits ( fig . preliminary laboratory tests detected mild anemia ( hemoglobin concentration : 10.7 g / dl , hematocrit : 30.3% ) , and neutrophilic ( 8,240/l ) and eosinophilic ( 550/l ) leukocytosis . the patient had a sodium level of 119 mmol / l , potassium level of 4.2 mmol / l , albumin level of 2.9 g / dl , and prealbumin level of 5.3 mg / dl in serum . an abdominal ct scan indicated suspicious wall thickness in the prepyloric antrum , but no distinct mass - like lesion was observed . after 1 month , the patient underwent subtotal gastrectomy and d2 lymph node dissection . the resected gastric specimen comprised of 2 individual lesions : a moderately differentiated adenocarcinoma of type iic early gastric cancer ( t1an0m0 ) and a tubular adenoma . as was the case for the biopsy specimen described above , multiple parasite eggs , rhabditiform larvae , and adult worms presumably of s. stercoralis were found in normal gastric and duodenal gland pits . moreover , parasite eggs and adult worms were also observed within atypical glands of the gastric adeno carcinoma ( fig . 3c ) and scattered eosinophils were observed in the duodenum , and a microabscess was observed in one of the gastric regional lymph nodes ( fig . 3d ) . as the routine stool test failed to detect filariform larvae in fecal samples , pcr was performed on dna samples extracted from a formalin - fixed paraffin - embedded gastric tissue block , aiming to identify s. stercoralis . the following 2 pairs of specific primers used to identify the s. stercoralis 18s rrna gene have been previously described : forward 1 , 5-atcgtgtcggtggatcattc-3  ; reverse 1 , 5-ctattagcgccatttgcattc-3  ; forward 2 , 5-gaattccaagtaaacgtaagtcattagc-3  ; and reverse 2 , 5-tgcctctggatattgctcagttc-3  . a positive band was amplified at 114 and 101 bp for the targeted s. stercoralis gene and at 110 bp for the internal amplification control ( fig . the histopathology and molecular results were consistent with the presence of s. stercoralis within the gastric adenocarcinoma . the patient was treated with albendazole ( 400 mg twice daily ) for 7 days ; the patient s fever was subsequently alleviated , his inflammatory marker levels returned to within normal ranges , and he was discharged from the hospital . the patient was followed - up by monitoring and additional laboratory testing for 4 months postoperatively . s. stercoralis is an intestinal nematode parasite that may be able to reproduce in humans . s. stercoralis is transmitted from the soil and penetrates the skin , resulting in an infection . after such exposure , it can be transported to the respiratory system via the bloodstream . the parasite can then migrate along with swallowed sputum and enter the gastrointestinal tract where it matures , particularly in the duodenum and upper jejunum . internal autoinfection is a major differentiating characteristic of s. stercoralis ; it allows this helminth parasite to remain within the human body for years . several years after exposure , this can contribute to the development of a fatal disease . although infection may occur in both immunocompetent and immunocompromised individuals , immunocompromised patients in particular may tend to develop disseminated hyperinfection syndrome and septicemia involving multiple organic systems and resulting in potentially life - threatening complications . therefore , adequate diagnosis and treatment are critical in patients at high risk for complications due to s. stercoralis infection . unfortunately , s. stercoralis is difficult to diagnose clinically , and its laboratory diagnosis is commonly confirmed by the detection of filariform larvae in fecal samples . however , routine stool examination using conventional techniques may fail to identify larvae in up to 70% of cases , because the parasite load is very low and larval output is irregular and minimal . in the current case , although parasite eggs and adult worms were observed in both the gastric adenocarcinoma and the gastric pits of biopsied and resected gastric specimens , the stool test failed to detect larvae in the patient s fecal samples . accordingly , we performed pcr in an effort to detect the presence of s. stercoralis in formalin - fixed paraffin - embedded gastric tissues . the patient reported here had mild eosinophilia in serum ; meanwhile , scattered eosinophils were rarely observed in the stomach but frequently observed in duodenal tissue . in addition , a microabscess was found in a gastric regional lymph node , which is indicative of febrile , disseminated infection . elisa , a common serology test , was not performed because it exhibits decreased specificity in patients who are already immunosuppressed . thus , histopathological examination of tissue or aspirated material could aid in determining the definitive diagnosis . s. stercoralis can inhabit any segment of the gastrointestinal tract , but cases of gastric involvement are rare , because the stomach is not an ideal site . thus , s. stercoralis infection could lead to gastric ulcers . to the best of our knowledge , the case reported herein is the first case of comorbid gastric adenocarcinoma and s. stercoralis infection in an elderly patient with a long history of diabetes mellitus . we identified parasite eggs and worms within the gastric adenocarcinoma and adenoma and confirmed the presence of s. stercoralis by pcr using samples from the same tissue . two recent systematic literature reviews of s. stercoralis infection cases suggest that corticosteroid use is a primary risk factor and can trigger the development of severe strongyloidiasis . unfortunately , data from the literature do not clarify whether strongyloidiasis associated with corticosteroid use depends considerably on the duration and cumulative dosage of the associated treatment . regarding treatment , ivermectin is reported to be the most effective drug for the treatment of strongyloidiasis , but albendazole might be a valid option in many countries with poor availability of ivermectin . however , standard treatments for strongyloidiasis , especially in the presence of hyperinfection or dissemination , remain a debated issue . in summary , s. stercoralis can result in disseminated hyperinfection syndrome and septicemia that could rapidly become fatal . however , stool examination , which is the conventional method for s. stercoralis detection , has very low sensitivity . our experience with this case suggests that endoscopic biopsies and pcr are alternative methods for diagnosing strongyloidiasis .
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 .