CASE REPORT A 28-year-old man from Equatorial Guinea presented with debilitating fatigue, persistent shortness of breath for the past year, and notable episodes of hematochezia and melena for the past week. Laboratory workup indicated the presence of iron deficiency anemia as the sole significant finding. Colonoscopy revealed a diffuse area of mildly erythematous mucosa in the rectal-sigmoid colon (Figure 1). Biopsy revealed colonic mucosa with calcified parasitic eggs (Figure 1), initially read by pathology as morphologically suggestive of Schistosoma mansoni eggs and later confirmed to be Schistosoma intercalatum by gene sequencing. The patient was treated with praziquantel, resulting in improved symptoms, cessation of bleeding, and stabilization of hemoglobin levels. The endoscopic appearance of lesions was variable, ranging from granulomas to polyps to ulcerations.1,2 In a case review of 46 patients with colonic schistosomiasis, as many as 12 patients were initially misdiagnosed as ulcerative colitis, Crohn's disease, and ischemic colitis.3,4 It is of utmost importance to maintain a low threshold for conducting endoscopic biopsies in patients who are at risk of parasitic infections, particularly those caused by the Schistosoma species.Figure 1.: Diffuse area of mildly erythematous mucosa from 30 cm from the anal verge found in the rectal-sigmoid colon (A, arrows). Pathology showing multiple Schistosoma eggs (B, arrows).DISCLOSURES Author contributions: HE Lee: Made the most significant contribution to the case report in terms of drafting, data gathering, and revising the report. R. Abrol: Made significant contribution in revising and guiding the first author by gathering references and editing drafts. K. Humphrey and S. Qiu: Assisted with obtaining pathology, imaging, and explaining histologic findings. S. McLellan and SK Merwat: Helped with review of drafts and overall guidance. HE Lee is the article guarantor. Financial disclosure: None to report. Previous presentation: This case was presented at 13th Annual Quality and Research Forum at UTMB; April 2023; Galveston, TX. Informed consent was obtained for this case report.

Introduction: Although uncommon in the United States, Schistosoma species are blood flukes that affect more than 200 million in many developing countries including Africa. It is often misdiagnosed by physicians in non-endemic areas. Schistosomiasis can involve a variety of organ systems, notably gastrointestinal and genitourinary systems. Case Description/Methods: A 28-year-old patient from Equatorial Guinea with no past medical history presented as a transfer from outside hospital with hemoglobin of 5.8 g/dL. The patient had been having severe fatigue for the past year, and significant hematochezia for the past week. He had no contributory surgical, family or social history. The patient was tachycardic with conjunctival pallor, but had otherwise unremarkable physical exam. Admission labs revealed iron deficiency anemia with hemoglobin of 8.1 g/dL. Other complete cell counts, coagulation studies, hemolysis studies, blood smear, fecal ova and parasites, and infectious workup were unremarkable. Imaging was unremarkable. Colonoscopy showed a diffuse area of mildly erythematous mucosa in the recto-sigmoid colon. Biopsy revealed colonic mucosa with calcified parasitic eggs, later identified to be Schistosoma intercalatum. The patient was subsequently treated with praziquantel with improvement of the symptoms and stabilization of hemoglobin. Patient was safely discharged with plans for follow up. Discussion: There are reports highlighting atypical presentations of Schistosoma mansoni and hematobium species. Schistosoma intercalatum, though less prevalent, have been reported to cause rectal bleeding with inflammation of the rectum and colon. However, it is unusual for the parasite to cause such profound iron deficiency anemia as seen in our patient, especially without noticeable mucosal pathology. Diagnosis of Schistosoma species is made on the presence of ova in feces or in biopsies of rectal mucosa. The endoscopic appearance of lesions is variable, ranging from granulomas to polyps to ulcerations. In non-endemic areas, it is often misdiagnosed as ulcerative colitis, Crohn’s disease, and ischemic colitis. Therefore, it is important to maintain low threshold for endoscopic biopsy in patients at risk for parasitic infection, including Schistosoma species. In conclusion, this case serves as an example of presentation of an atypical parasite in the workup of GI bleed. Schistosoma species and a patient's geographic background should be considered when common etiology is ruled out in GI bleed (see Figure 1).Figure 1.: A: Diffuse area of mildly erythematous mucosa from 30cm from the anal verge found in the rectal-sigmoid colon. B: Map of Schistosoma species distribution and Equatorial Guinea (red arrow). C: Pathology showing multiple Schistosoma eggs (red arrows). D: Speciation gene sequencing at NIH consistent with S. intercalatum.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the coronavirus pandemic in 2019, commonly causes hepatic dysfunction. Liver injury ranges from mildly elevated liver enzymes to fulminant liver failure. Interestingly, there are cases that suggest a relationship between autoimmune hepatitis (AIH) in patients who either contracted coronavirus disease in 2019 (COVID-19) or were vaccinated against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We present a case of a 39-year-old female without a significant past medical history who presented with two weeks of jaundice, abdominal pain, nausea, and diarrhea. She had significantly elevated liver enzymes and conjugated hyperbilirubinemia. She also tested positive for SARS-CoV-2 but denied any respiratory symptoms; her vaccination status was up to date. She denied taking hepatotoxic agents, and the workup was negative for acute viral hepatitis. The F-actin antibody level was 22 units, but serum immunoglobulin (IgG), anti-nuclear (ANA), anti-smooth muscle, anti-mitochondrial, anti-liver/kidney microsomal-1, anti-soluble liver antigen, and anti-neutrophil cytoplasmic antibodies levels were not elevated. Computerized tomography of the abdomen and pelvis revealed hepatic hemangiomas. Eventually, a liver biopsy was performed, and histology showed active lymphoplasmacytic hepatitis with prominent regenerative changes and areas of confluent necrosis. The histologic findings, along with the patient's clinical course, were suggestive of autoimmune hepatitis. The patient was started on systemic steroids with an improvement of abdominal pain and jaundice, as well as an improvement of her liver chemical profile. She was discharged with plans for hepatology clinic follow-up. Here, we present a rare case of seronegative AIH in a patient with a recent COVID-19 infection and discuss the potential underlying mechanism. We call for further investigation into the relationship between autoimmune dysfunction and COVID-19, as well as the pathophysiology behind it. Analyzing how the virus causes autoimmune dysfunction may allow clinicians to more effectively treat patients suffering from sequelae of COVID-19 infection, and it is important not to exclude autoimmune hepatitis from the differential based on the initial autoimmune workup.

ABSTRACT Signet ring cell carcinoma, a type of gastrointestinal system-related cancer, rarely metastasizes to the skeletal muscle. We present signet ring-cell carcinoma in a 28-year-old man who presented with left lower extremity pain and swelling. Imaging showed thickening of the distal esophagus, intestines, and bladder wall. Endoscopy revealed friable gastric mucosa and stenosis in the ascending colon, but biopsies were unrevealing. Leg muscle biopsy showed metastatic adenocarcinoma with focal signet ring features. Carcinoembryonic antigen and cancer antigen 19-9 were elevated. A gastrointestinal primary tumor was suspected. Our case urges clinicians to consider this rare cancer in patients presenting with skeletal muscle mass.