Multifocal Osteomyelitis in an Adolescent Patient With Cat Scratch Disease.

Cat scratch disease (CSD) typically presents as a self-limiting lymphadenopathy associated with a cat bite or scratch and commonly affects children and young adults. Atypical manifestations, involving the eyes, nervous system, heart, liver, spleen, skin, and musculoskeletal system, could be severe and difficult to diagnose, and they could occur in 5%-20% of the cases. Herein, we report an unusual case of CSD with multifocal osteomyelitis. A 15-year-old girl presented with right axillary lymphadenopathy. Since she had a history of cat scratch, azithromycin was started for CSD. Two days later, she was readmitted to our hospital with severe back pain which required differential diagnosis. Lumbar spinal magnetic resonance imaging (MRI) revealed multifocal vertebral osteomyelitis. The patient was hospitalized, and then teicoplanin and cefotaxime were added to the azithromycin therapy. After excluding the possible other causes, the definitive diagnosis of osteomyelitis secondary to CSD was made upon the combination of the MRI scan findings of the vertebrae, histopathological investigation of excisional right axillary biopsy, positron-emission tomography/computed tomography (PET/CT), and Bartonella henselae serologies. Atypical manifestations of CSD are widely variable; therefore, it should be kept in mind in the differential diagnosis of severe musculoskeletal pain and osteomyelitis.