Purpose or Case Report: Cat-Scratch Disease (CSD) is an infectious disease that predominantly affects pediatric patients, usually ages 4-9 years old. The annual incidence is estimated at 4.5 patients per 100,000 population. CSD is primarily caused by B. henselae, an intracellular gram-negative bacillus; it is transmitted via scratch, lick, or bite from a cat. It presents with lymphadenopathy proximal to the site of inoculation; most commonly, this is axillary, epitrochlear, cervical, or inguinal lymphadenopathy. While CSD can be diagnosed clinically and has objective findings on histopathology, the imaging findings are unclear and have been debated in the literature. As such, we sought to clarify the multimodal imaging findings associated with CSD. We performed a review of the literature to highlight the existing radiological consensus. We also contribute several of our own new cases from our institution.
Methods & Materials: We report multiple cases of patients with confirmed CSD who received any form of imaging. We review the multimodal imaging and relevant clinical findings of each case. In addition, we performed a literature review of existing cases describing the imaging findings to corroborate our data and improve the utility of imaging in providing a differential diagnosis.
Results: Our review of multimodal imaging methods for CSD highlighted useful information in aiding the diagnosis of CSD. On ultrasound, CSD was most commonly a hypoechoic mass with central hyperemia; the presence of mass asymmetry and a hyperechoic hilum was most specific for CSD. On CT, CSD presented as a heterogenous mass isodense to muscle, with central hypodensity. On MR, CSD was also isointense to muscle on T1, with hyperintense signal on fat-suppressed T2.
Conclusions: Cat-Scratch Disease (CSD) is an underdetected diagnosis, common in the pediatric population. In this study, we aimed to highlight the multimodal imaging findings of CSD, both in the existing literature and also in newly contributed cases we identified from our institution. We were able to identify several key findings on imaging that might suggest a diagnosis of CSD. Our hope is to provide information that can aid in differential diagnosis, leading to earlier diagnosis and decreased delays in treatment.