Lumbar intravertebral disc herniation secondary to idiopathic calcific discitis

Calcific discitis is a well recognized entity in the paediatric population but more recently has been increasingly reported in adults. It typically involves the lower thoracic vertebrae and is of unknown aetiology. Herniation of the calcified fragment is rare but typically occurs out through the annulus fibrosus into the canal space. Herein we describe the first reported case of calcific discitis involving the lumbar vertebrae with subsequent herniation of the calcified disc into and through the anterior aspect of the L5 vertebra. The patient first presented with a history of right back pain and leg sciatica. Radiographic imaging demonstrated calcification within the L4/5 interspace, which was managed with simple analgesia. She subsequently re-presented 24-months later with worsening sciatica, right leg weakness and faecal incontinence. No evidence of cord or root compression was noted on MRI. However, an abnormality was noted at the anterior body of L5 with evidence of superior endplate depression and marrow signal change. Subsequent radionucleide bone studies confirmed a solitary focus of increased linear activity extending across the width of the L4-L5 interspace. Her symptoms were managed medically. Serial radiographic imaging demonstrated regression of the disc space calcification and healing of the L5 fracture. Despite its sinister presentation this condition was self-limiting. We describe the radiographic evolution of this pathology and postulate a putative hypothesis through which it may have arisen.