Suspected Hepatosplenic Cat Scratch Disease with No Major Symptoms and Negative Serology: A Case Report

BACKGROUND Hepatosplenic cat scratch disease, a form of atypical cat scratch disease, is rare in immunocompetent adults, and presentations can mimic those of potentially lethal diseases. Nonetheless, diagnosis can be challenging due to underrecognition of the disease, as well as variability in the sensitivity of diagnostic testing. CASE REPORT A 39-year-old woman with no major medical history presented to the Emergency Department with right lower quadrant abdominal pain. Vital signs were stable, and laboratory findings were nonsignificant. Abdominal computed tomography (CT) with contrast was nonsignificant except for multiple low-enhancing nodules in the liver and spleen. Appendicitis was clinically suspected, and intravenous cefmetazole was initiated, followed by levofloxacin 500 mg orally once daily, plus metronidazole 500 mg orally once daily for 7 days. Her abdominal symptoms resolved a week later, but hepatosplenic nodules were still evident on CT. A thorough medical interview revealed frequent cat exposure. Despite negative indirect fluorescent antibody assay results for anti-Bartonella henselae immunoglobulin M and immunoglobulin G, cat scratch disease was strongly suspected. She was treated with rifampicin 300 mg orally twice daily and azithromycin 500 mg once daily on the first day, followed by 250 mg once daily thereafter for 2 weeks in total. Two months after treatment, abdominal CT revealed resolution of the hepatosplenic nodules. CONCLUSIONS Although hepatosplenic cat scratch disease is rare in immunocompetent adults, it should be suspected in patients with multiple hepatosplenic nodules, even with negative serologic test results. In such cases, timely initiation of antibiotics can be beneficial.