Petit's hernia in the differential diagnosis of atypical low back pain: A case report

Background Lumbar hernias are uncommon defects of the posterior abdominal wall, accounting for less than 1.5% of all abdominal hernias. This report aims to present a case of a Petit hernia mimicking low back pain and radiculopathy, highlighting its importance in the differential diagnosis of atypical low back pain to avoid unnecessary spine surgeries. Case presentation A 75-year-old female patient with a history of lumbar laminectomies (L3-L5) six years prior presented with chronic low back pain radiating to the right gluteus and iliac crest. The pain was exacerbated by standing and sitting, and it worsened after receiving myofascial infiltrations. Neurological examination revealed 5/5 muscle strength, preserved deep tendon reflexes, and negative Lasègue and Patrick signs bilaterally; the only notable findings were hypersensitivity in the right L1 dermatome and an antalgic gait. X-rays and magnetic resonance imaging demonstrated degenerative changes and L1-L2 spinal stenosis. However, these findings were insufficient to explain the clinical picture. A computed tomography scan and a focused ultrasound at the referred site of pain confirmed a posterior muscular wall defect with retroperitoneal fat herniation directly through the inferior lumbar triangle. In conjunction with the General Surgery service, a hernia reduction and polypropylene mesh placement were performed, resulting in the complete resolution of symptoms. Conclusions Petit hernia is a rare cause of chronic low back pain. Its diagnosis requires a high index of clinical suspicion and clear imaging confirmation, which are essential to rule out radicular pathology, prevent unnecessary spine surgeries, and ensure successful surgical repair with a mesh.