Nonneoplastic low T2 signal mass posterior to odontoid process related to rheumatoid arthritis (RA), degenerative change with chronic abnormal motion, and atlantoaxial subluxation, without significant calcification
Not to be confused with
Crowned dens syndrome: Fever with cervicooccipital junction pain, stiffness with associated calcification of transverse ligament, and nonenhancing retroodontoid soft tissue; associated with calcium pyrophosphate dihydrate crystal deposition disease (CPPD) or hydroxyapatite deposition
Pseudogout: Arthritis caused by CPPD crystal inflammation with symptoms like gout
Tophaceous pseudogout: Large accumulation of material giving pattern of soft tissue tumor with mass effect/cord compression
RA soft tissue posterior to odontoid referred to as pannus
IMAGING
General Features
CT Findings
MR Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Gross Pathologic & Surgical Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Reporting Tips
Selected References
Shi J et al: Thinking beyond pannus: a review of retro-odontoid pseudotumor due to rheumatoid and non-rheumatoid etiologies. Skeletal Radiol. 48(10):1511-23, 2019
Yu SH et al: Retro-odontoid pseudotumor without atlantoaxial subluxation or rheumatic arthritis. Korean J Neurotrauma. 12(2):180-4, 2016
Ea HK et al: Diagnosis and clinical manifestations of calcium pyrophosphate and basic calcium phosphate crystal deposition diseases. Rheum Dis Clin North Am. 40(2):207-29, 2014
Chang EY et al: Frequency of atlantoaxial calcium pyrophosphate dihydrate deposition at CT. Radiology. 269(2):519-24, 2013
Mwaka ES et al: Calcium pyrophosphate dehydrate crystal deposition in the ligamentum flavum of the cervical spine: histopathological and immunohistochemical findings. Clin Exp Rheumatol. 27(3):430-8, 2009
Taniguchi A et al: Painful neck on rotation: diagnostic significance for crowned dens syndrome. J Neurol. 257(1):132-5, 2009
Fenoy AJ et al: Calcium pyrophosphate dihydrate crystal deposition in the craniovertebral junction. J Neurosurg Spine. 8(1):22-9, 2008
Salaffi F et al: The crowned dens syndrome as a cause of neck pain: clinical and computed tomography study in patients with calcium pyrophosphate dihydrate deposition disease. Clin Exp Rheumatol. 26(6):1040-6, 2008
Doita M et al: Calcium pyrophosphate dihydrate deposition in the transverse ligament of the atlas: an unusual cause of cervical myelopathy. Skeletal Radiol. 36(7):699-702, 2007
Goto S et al: Crowned Dens syndrome. J Bone Joint Surg Am. 89(12):2732-6, 2007
Feydy A et al: Cervical spine and crystal-associated diseases: imaging findings. Eur Radiol. 16(2):459-68, 2006
Lin SH et al: Cervical myelopathy induced by pseudogout in ligamentum flavum and retro-odontoid mass: a case report. Spinal Cord. 44(11):692-4, 2006
Finckh A et al: The cervical spine in calcium pyrophosphate dihydrate deposition disease. A prevalent case-control study. J Rheumatol. 31(3):545-9, 2004
Muthukumar N et al: Tumoral calcium pyrophosphate dihydrate deposition disease of the ligamentum flavum. Neurosurgery. 53(1):103-8; discussion 108-9, 2003
Assaker R et al: Foramen magnum syndrome secondary to calcium pyrophosphate crystal deposition in the transverse ligament of the atlas. Spine (Phila Pa 1976). 26(12):1396-400, 2001
Baysal T et al: The crowned dens syndrome: a rare form of calcium pyrophosphate deposition disease. Eur Radiol. 10(6):1003-5, 2000
Kakitsubata Y et al: Calcium pyrophosphate dihydrate crystal deposition in and around the atlantoaxial joint: association with type 2 odontoid fractures in nine patients. Radiology. 216(1):213-9, 2000
Fye KH et al: Compressive cervical myelopathy due to calcium pyrophosphate dihydrate deposition disease: report of a case and review of the literature. Arch Intern Med. 159(2):189-93, 1999
Resnick D et al: Vertebral involvement in calcium pyrophosphate dihydrate crystal deposition disease. Radiographic-pathological correlation. Radiology. 153(1):55-60, 1984
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KEY FACTS
Terminology
Imaging
Top Differential Diagnoses
Clinical Issues
Diagnostic Checklist
TERMINOLOGY
Synonyms
Periodontoid pseudotumor
Definitions
Nonneoplastic low T2 signal mass posterior to odontoid process related to rheumatoid arthritis (RA), degenerative change with chronic abnormal motion, and atlantoaxial subluxation, without significant calcification
Not to be confused with
Crowned dens syndrome: Fever with cervicooccipital junction pain, stiffness with associated calcification of transverse ligament, and nonenhancing retroodontoid soft tissue; associated with calcium pyrophosphate dihydrate crystal deposition disease (CPPD) or hydroxyapatite deposition
Pseudogout: Arthritis caused by CPPD crystal inflammation with symptoms like gout
Tophaceous pseudogout: Large accumulation of material giving pattern of soft tissue tumor with mass effect/cord compression
RA soft tissue posterior to odontoid referred to as pannus
IMAGING
General Features
CT Findings
MR Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Gross Pathologic & Surgical Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Reporting Tips
Selected References
Shi J et al: Thinking beyond pannus: a review of retro-odontoid pseudotumor due to rheumatoid and non-rheumatoid etiologies. Skeletal Radiol. 48(10):1511-23, 2019
Yu SH et al: Retro-odontoid pseudotumor without atlantoaxial subluxation or rheumatic arthritis. Korean J Neurotrauma. 12(2):180-4, 2016
Ea HK et al: Diagnosis and clinical manifestations of calcium pyrophosphate and basic calcium phosphate crystal deposition diseases. Rheum Dis Clin North Am. 40(2):207-29, 2014
Chang EY et al: Frequency of atlantoaxial calcium pyrophosphate dihydrate deposition at CT. Radiology. 269(2):519-24, 2013
Mwaka ES et al: Calcium pyrophosphate dehydrate crystal deposition in the ligamentum flavum of the cervical spine: histopathological and immunohistochemical findings. Clin Exp Rheumatol. 27(3):430-8, 2009
Taniguchi A et al: Painful neck on rotation: diagnostic significance for crowned dens syndrome. J Neurol. 257(1):132-5, 2009
Fenoy AJ et al: Calcium pyrophosphate dihydrate crystal deposition in the craniovertebral junction. J Neurosurg Spine. 8(1):22-9, 2008
Salaffi F et al: The crowned dens syndrome as a cause of neck pain: clinical and computed tomography study in patients with calcium pyrophosphate dihydrate deposition disease. Clin Exp Rheumatol. 26(6):1040-6, 2008
Doita M et al: Calcium pyrophosphate dihydrate deposition in the transverse ligament of the atlas: an unusual cause of cervical myelopathy. Skeletal Radiol. 36(7):699-702, 2007
Goto S et al: Crowned Dens syndrome. J Bone Joint Surg Am. 89(12):2732-6, 2007
Feydy A et al: Cervical spine and crystal-associated diseases: imaging findings. Eur Radiol. 16(2):459-68, 2006
Lin SH et al: Cervical myelopathy induced by pseudogout in ligamentum flavum and retro-odontoid mass: a case report. Spinal Cord. 44(11):692-4, 2006
Finckh A et al: The cervical spine in calcium pyrophosphate dihydrate deposition disease. A prevalent case-control study. J Rheumatol. 31(3):545-9, 2004
Muthukumar N et al: Tumoral calcium pyrophosphate dihydrate deposition disease of the ligamentum flavum. Neurosurgery. 53(1):103-8; discussion 108-9, 2003
Assaker R et al: Foramen magnum syndrome secondary to calcium pyrophosphate crystal deposition in the transverse ligament of the atlas. Spine (Phila Pa 1976). 26(12):1396-400, 2001
Baysal T et al: The crowned dens syndrome: a rare form of calcium pyrophosphate deposition disease. Eur Radiol. 10(6):1003-5, 2000
Kakitsubata Y et al: Calcium pyrophosphate dihydrate crystal deposition in and around the atlantoaxial joint: association with type 2 odontoid fractures in nine patients. Radiology. 216(1):213-9, 2000
Fye KH et al: Compressive cervical myelopathy due to calcium pyrophosphate dihydrate deposition disease: report of a case and review of the literature. Arch Intern Med. 159(2):189-93, 1999
Resnick D et al: Vertebral involvement in calcium pyrophosphate dihydrate crystal deposition disease. Radiographic-pathological correlation. Radiology. 153(1):55-60, 1984
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