A 25-year-old female with a 3-year history of rheumatoid arthritis (RA) underwent a 3-dimensional volume-rendered computed tomography (CT) scan of the thoracic spine for further investigation of thoracic spine abnormalities incidentally discovered on a routine chest X-ray. Her height was 145 cm, and she was shorter than her siblings (two brothers and a sister). She had no neck pain or torticollis. Her neurological examination findings were unremarkable. Neither additional anomalies nor tendencies toward other similar anomalies were reported or seen in either her or other members of her family. She had been previously treated with methotrexate, sulfasalazine, prednisolone, and nabumetone. A 3-dimensional volume-rendered CT scan revealed a small right supranumerary T2 hemivertebra with an extra rib and pedicle as well as segmentation failure at T1 to 5, resulting in thoracic scoliosis (Fig. 1). Segmentation defects of the vertebrae cause kyphosis and scoliosis, contributing to common health problems that present as back and neck pain, disability, cosmetic disfigurement, and functional distress. The etiologies of vertebral segmentation disorders are thought to involve interactions between genetic and environmental factors. Recent studies have indicated that a periodic wave of gene expression, termed the "segmentation clock," triggers the rhythmic production of segments in vertebrates. Our patient exhibited anterior failure of vertebral body formation (type 1) and a single vertebra of the posterior hemivertebrae; thus, her condition could be classified as (surgical/anatomical) congenital kyphosis/kyphoscoliosis. She is being followed up and is not being considered for any treatment for the segmentation defects of her thoracic vertebrae.