Two Cases of Singular Sacral S1 Butterfly Vertebra.

A butterfly vertebra is an uncommon but clinically and radiologically significant pathology. The etiological factor of this pathology is a congenital defect in the formation of the vertebral body during embryogenesis, resulting in a cleft within the vertebral body that, in an X-ray, resembles the shape of a butterfly. Butterfly vertebrae are most often found in the thoracic and lumbar spine and more rarely in the sacral region. The clinical manifestations of this condition do not differ from the symptoms of other diseases, and it may also be asymptomatic. Only the recognition of its characteristic radiologic signs allows for accurate and timely diagnosis, as well as differentiation from other pathological processes such as fractures, metastases, and inflammation. In these cases, magnetic resonance imaging is the first-choice method. An important aspect in recognizing this pathology is its correlation with other congenital syndromes, even in cases of a single vertebral defect. We present 2 cases with an isolated S1 butterfly vertebra. The first is a 47-year-old male who presented to the hospital with complaints of chronic pain in the lower back and sacral region, more pronounced on the right side. The second is of a 39-year-old male who also presented to the hospital with chronic pain. All diagnostic modalities for this pathology have been used to demonstrate high-quality pictures, including X-ray, computed tomography (CT), and magnetic resonance imaging (MRI).