Question: A 53-year-old woman presented with abdominal pain, nausea, vomiting, and weight loss of several months’ duration. Two years earlier, she was diagnosed with non-Hodgkin lymphoma and malignant pleural effusions for which she underwent treatment. She was on maintenance rituximab upon admission. She had presented several times in the previous months with similar symptoms and thorough investigations could not confirm lymphomatous involvement of the gastrointestinal tract. Upon this admission, an upper gastrointestinal series with small-bowel follow-through revealed a slow intestinal transit time and nodular and thickened mucosal folds throughout the small bowel, findings suspicious for lymphoma. She then developed multiple febrile episodes. Upper endoscopy and colonoscopy were repeated and showed innumerable small, superficial ulcers throughout her upper and lower gastrointestinal tract (Figure A, arrow at colonic ulcer), as well as upper esophageal candidiasis for which she was started on fluconazole. Multiple biopsies were taken, which confirmed the presence of acute duodenal and colonic ulcers (Figure B, arrows at residual crypts; H&E stain, original magnification, ×400); there was no evidence of lymphoma. Grocott, acid fast, and cytomegalovirus stains performed on the biopsies were negative. Clostridium difficile toxin assays, stool ova, and parasite examinations and stool cultures were also negative. During her hospital stay, she had waxing and waning mental status. She developed a left-sided, exudative pleural effusion. After pleurocenteses failed to show malignant cells, pleural and mediastinal lymph node biopsies were taken. There was no evidence of lymphoma, but necrotizing granulomatous lymphadenitis was noted. Gram, Grocott, and acid fast stains were negative for infectious organisms. A Warthin–Starry stain demonstrated numerous (black) organisms (Figure C; original magnification, ×600), and these organisms were retrospectively identified on the prior duodenal and colonic ulcer biopsies. What is the diagnosis? Look on page 1046 for the answer and see the Gastroenterology web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI. The presence of Warthin–Starry—positive organisms in necrotizing granulomatous lymphadenitis is consistent with B henselae infection. An immunohistochemical stain for B henselae is confirmatory, as noted in the duodenal and colonic ulcers (Figure D; original magnification, ×400) of this case. The patient was started on rifampin and doxycycline followed by ceftriaxone and her abdominal pain, nausea, and vomiting improved. Common clinical manifestations of infection with B henselae are cat-scratch disease (fever and localized lymphadenopathy), fever of unknown origin and hepatosplenic disease with microabscesses/granulomas evident on imaging studies. B henselae is transmitted to humans by a cat scratch, bite, lick, or even possibly from fleas (of note, the patient in our report did own 4 outdoor cats, but she did not recall being scratched or bitten). With improved therapies over the last several years, vascular proliferative lesions (bacillary angiomatosis and bacillary peliosis) are no longer common in immunosuppressed patients. Although a few cases showing endoscopic and pathologic evidence of B henselae infection involving the gastrointestinal tract have been documented in the literature, the diagnoses were bacillary angiomatosis. In one report, erythematous nodules and ulcerations were described in the colon of a man with HIV and Crohn's disease who presented with bloody diarrhea and abdominal pain; he was diagnosed with bacillary angiomatosis.1Huh Y.B. Rose S. Schoen R.B. et al.Colonic bacillary angiomatosis.Ann Intern Med. 1996; 124: 735-737Crossref PubMed Scopus (14) Google Scholar Bacillary angiomatosis, with the endoscopic appearance of ulcerated nodular lesions in the esophagus, stomach, and duodenum, was also described in a 38-year-old woman with HIV who presented with hematemesis.2Chetty R. Sabaratnam R.M. Upper gastrointestinal bacillary angiomatosis causing hematemesis: a case report.Int J Surg Pathol. 2003; 11: 241-244Crossref PubMed Scopus (17) Google Scholar The patient in the current report did not have HIV, but was immunosuppressed owing to treatment of lymphoma. Importantly, her gastrointestinal tract involvement by B henselae did not present as the erythematous nodules of bacillary angiomatosis, as in previous reports. Rather, the organism caused small, nondescript ulcers (another view of the ulcers is shown in Figure E; one is at the arrow). Although uncommon, B henselae infection should be included in the differential diagnosis when a patient develops small ulcers throughout the gastrointestinal tract that are suspected of being infectious in etiology but fail to stain for the more routine organisms such as cytomegalovirus, fungus, and acid-fast bacilli.