This case study reports a typical clinical course of cat-scratch disease (CSD) in an infant without epidemiological data and presenting bilateral submandibular lymphadenopathy. The authors describe clinical course, ultrasound images, diagnosis and prognosis. Polymerase chain reaction (PCR) detected and identified B. quintana in lymph node samples. B. henselae currently thought to be the causative agent of CSD was not detected. The PCR assays for B. quintana and B. henselae should be available for the investigation of lymphadenopathy, even if the infant has not had either cat or dog contact.