Occult strongyloides stercoralis infection masquerading as a drug reaction with eosinophilic pneumonia

Background: Pseudomelanosis or melanosis duodeni is seen in association with drugs, microorganisms or occasional bleeding, usually from peptic ulceration. We present a case of Strongyloides stercoralis presenting as pseudomelanosis duodeni during anemia workup after patient's initial presentation as eosinophilic pneumonia. Case presentation: The patient is a 77 year-old female with a history of diastolic congestive heart failure, chronic kidney disease, diabetes mellitus, and hypertension who presented for evaluation of black stool. Two months earlier, in her prior admission for acute eosinophilic pneumonitis, the patient's hematocrit was 26%. In her current admission with heme-positive dark stool on exam, the hematocrit dropped to 19%. The patient underwent esophagogastroduodenoscopy to identify the source of bleeding. The upper endoscopy revealed three non-bleeding ulcers in the gastric antrum and discoloration of the duodenal bulb and second portion of the duodenum. By histology, the duodenal biopsies showed areas of hemosiderin-laden macrophages in the lamina propria, focal helminth eggs and larvae in the crypt lumen with sizes ranging from 35-65 microns x ~20 microns. Polymerase chain reaction of the paraffin embedded tissue with 28S primer set detected Strongyloides stercoralis DNA, confirming the histologic findings. Given the confirmation of Strongyloides stercoralis, the patient's initial presentation of eosinophilic pneumonia (Loeffler syndrome) may be a result of the parasitic infection or the successful response to steroid treatment for acute eosinophilic pneumonia caused Strongyloidiasis hyperinfection. The patient's symptoms were improved with Ivermectin and hematocrit level increased to 28%. Conclusions: This case highlights the importance in recognition of helminth infection in the evaluation of eosinophilic pneumonia and pseudomelanosis duodeni