Unilateral Dense Pedicle

• Spondylolysis: Stress sclerosis on the contralateral side results in a dense pedicle. The case presented above demonstrates a dense left L5 pedicle (white arrow) and an old right L5 pars fracture (pink arrow).
• Benign tumors: Osteoid osteoma and osteoblastoma may cause a painful rigid scoliosis, with the lesion found on the concave side of the curve. Bone island uncommonly affects the pedicles.
• Malignant tumors: Blastic metastases (most common malignant cause of a unilateral dense pedicle). Other malignant tumors rarely present with a unilateral dense pedicle (e.g., lymphoma, multiple myeloma, Ewing sarcoma).
• Iatrogenic: Laminectomy (most commonly contralateral to the dense pedicle)
• Infection: Rarely affects the pedicle in isolation.
• Agenetic or hypoplastic pedicle or facet: The dense pedicle in on the opposite side to the agenetic or hypoplastic pedicle or facet.
• Miscellaneous: Tuberous sclerosis has an affinity for the posterior elements when it occurs in the spine, with multiple sclerotic pedicles being a frequent finding. Rarely Paget disease, fibrous dysplasia, and sarcoidosis, may affect the pedicle in isolation.

References

Yochum TR, Sellers LT, Oppenheimer DA, Peterson CK, Kirton CW, Dal Mas EC, Anderson AL. The sclerotic pedicle--how many causes are there? Skeletal Radiol. 1990;19(6):411-7.