Thinking beyond pannus: a review of retro-odontoid pseudotumor due to rheumatoid and non-rheumatoid etiologies

  • Junzi ShiEmail author
  • Joerg Ermann
  • Barbara N. Weissman
  • Stacy E. Smith
  • Jacob C. Mandell
Review Article


Retro-odontoid pseudotumor, or mass-like retro-odontoid soft tissue thickening, is an uncommon but important imaging finding that may be associated with rheumatoid arthritis, crystal deposition diseases, as well as non-inflammatory conditions such as cervical degenerative changes and mechanical alterations. Retro-odontoid pseudotumor is commonly associated with atlantoaxial microinstability or subluxation. MRI and CT have an important role in the detection and diagnosis of retro-odontoid pseudotumor. However, due to a wide range of imaging characteristics and ambiguous etiology, it is a frequently misunderstood entity. The purpose of this article is to review relevant anatomy of the craniocervical junction; describe various imaging appearances, pathophysiology and histology in both rheumatoid and non-rheumatoid etiologies; and discuss differential diagnosis of retro-odontoid pseudotumor in order to help guide clinical management.


Atlantoaxial Cervical spine Odontoid Pannus Retro-odontoid pseudotumor Rheumatoid arthritis 


Compliance with ethical standards

The above authors have no disclosures. The work has not been previously presented or published elsewhere. No IRB approval was required.

Conflict of interest

The authors declare that they have no conflicts of interest.


  1. 1.
    Sze G, Brant-Zawadzki MN, Wilson CR, Norman D, Newton TH. Pseudotumor of the craniovertebral junction associated with chronic subluxation: MR imaging studies. Radiology. 1986;161(2):391–4.Google Scholar
  2. 2.
    Joaquim AF, Appenzeller S. Cervical spine involvement in rheumatoid arthritis—a systematic review. Autoimmun Rev. 2014;13(12):1195–202.Google Scholar
  3. 3.
    Boden SD, Dodge LD, Bohlman HH, Rechtine GR. Rheumatoid arthritis of the cervical spine. A long-term analysis with predictors of paralysis and recovery. J Bone Joint Surg. 1993;75(9):1282–97.Google Scholar
  4. 4.
    Riise T, Jacobsen BK, Gran JT. High mortality in patients with rheumatoid arthritis and atlantoaxial subluxation. J Rheumatol. 2001;28(11):2425–9.Google Scholar
  5. 5.
    Dvorak J, Schneider E, Saldinger P, Rahn B. Biomechanics of the craniocervical region: the alar and transverse ligaments. J Orthop Res. 1988;6(3):452–61.Google Scholar
  6. 6.
    Dohzono S, Suzuki A, Koike T, et al. Factors associated with retro-odontoid soft-tissue thickness in rheumatoid arthritis. J Neurosurg Spine. 2016;25:580–5.Google Scholar
  7. 7.
    Tojo S, Kawakami R, Yonenaga T, Hayashi D, Fukuda K. Factors influencing on retro-odontoid soft-tissue thickness: analysis by magnetic resonance imaging. Spine (Phila Pa 1976). 2013;38(5):401–6.Google Scholar
  8. 8.
    Hakan T. Atlas: a unique vertebra that takes its name from a Hemitheos in Greek mythology, atlas. World Spinal Column J. 2010;1(3):212–4.Google Scholar
  9. 9.
    Tubbs RS, Hallock JD, Radcliff V, et al. Ligaments of the craniocervical junction. J Neurosurg Spine. 2011;14(6):697–709.Google Scholar
  10. 10.
    Menezes AH, Traynelis VC. Anatomy and biomechanics of normal craniovertebral junction (a) and biomechanics of stabilization (b). Childs Nerv Syst. 2008;24(10):1091–100.Google Scholar
  11. 11.
    Krauss WE, Bledsoe JM, Clarke MJ, Nottmeier EW, Pichelmann MA. Rheumatoid arthritis of the craniovertebral junction. Neurosurgery. 2010;66(SUPPL. 3):83–95.Google Scholar
  12. 12.
    Sangeorzan A, Sangeorzan B. Subtalar joint biomechanics: from normal to pathologic. Foot Ankle Clin. 2018;23(3):341–52.Google Scholar
  13. 13.
    Wagner FV, Negrão JR, Campos J, et al. Capsular ligaments of the hip: anatomic, histologic, and positional study in cadaveric specimens with MR arthrography. Radiology. 2012;263(1):189–98.Google Scholar
  14. 14.
    Panjabi M, Dvorak J, Crisco J III. Flexion, extension, and lateral bending of the upper cervical spine in response to alar ligament transections. J Spinal Disord. 1991;4(2):157–67.Google Scholar
  15. 15.
    Vetti N, Alsing R, Kråkenes J, et al. MRI of the transverse and alar ligaments in rheumatoid arthritis: feasibility and relations to atlantoaxial subluxation and disease activity. Neuroradiology. 2010;52(3):215–23.Google Scholar
  16. 16.
    Child Z, Rau D, Lee MJ, et al. The provocative radiographic traction test for diagnosing craniocervical dissociation: a cadaveric biomechanical study and reappraisal of the pathogenesis of instability. Spine J. 2016;16(9):1116–23.Google Scholar
  17. 17.
    Fielding JW, Cochran GVB, Lawsing JF, Hohl M. Tears of the transverse ligament of the atlas. A clinical and biomechanical study. J Bone Joint Surg Am. 1974;56(8):1683–91.Google Scholar
  18. 18.
    Joaquim AF, Ghizoni E, Tedeschi H, Appenzeller S, Riew KD. Radiological evaluation of cervical spine involvement in rheumatoid arthritis. Neurosurg Focus. 2015;38(4):E4.Google Scholar
  19. 19.
    El-Khouri M, Mourão MA, Tobo A, Battistella LR, Herrero CFP, Riberto M. Prevalence of atlanto-occipital and atlantoaxial instability in adults with Down syndrome. World Neurosurg. 2014;82(1–2):215–8.Google Scholar
  20. 20.
    Resnick D, Kang HS, Pretterklieber ML. Chapter 16: rheumatoid arthritis. In: Internal derangement of joints. 2nd ed. Philadelphia: Saunders; 2006. p. 240–4.Google Scholar
  21. 21.
    Camacho da Corte F, Nuno N. Cervical spine instability in rheumatoid arthritis. Eur J Orthop Surg Traumatol. 2014;24:S83.Google Scholar
  22. 22.
    Takeuchi M, Yasuda M, Takahashi E, Funai M, Joko M, Takayasu M. A large retro-odontoid cystic mass caused by transverse ligament degeneration with atlantoaxial subluxation leading to granuloma formation and chronic recurrent microbleeding case report. Spine J. 2011;11(12):1152–6.Google Scholar
  23. 23.
    Barbagallo GMV, Certo F, Visocchi M, Palmucci S, Sciacca G, Albanese V. Disappearance of degenerative, non-inflammatory, retro-odontoid pseudotumor following posterior C1-C2 fixation: case series and review of the literature. Eur Spine J. 2013;22(SUPPL.6):S879.Google Scholar
  24. 24.
    Lu K, Lee TC. Spontaneous regression of periodontoid pannus mass in psoriatic atlantoaxial subluxation. Case report. Spine (Phila Pa 1976). 1999;24(6):578–81.Google Scholar
  25. 25.
    Rajak R, Wardle P, Rhys-Dillon C, Martin JC. Odontoid pannus formation in a patient with ankylosing spondylitis causing atlanto-axial instability. BMJ Case Rep. 2012;2012.
  26. 26.
    Kauppi M, Neva MH. Sensitivity of lateral view cervical spine radiographs taken in the neutral position in atlantoaxial subluxation in rheumatic diseases. Clin Rheumatol. 1998;17(6):511–4.Google Scholar
  27. 27.
    Jackson H. The diagnosis of minimal atlanto-axial subluxation. Br J Radiol. 1950;23(275):672–4.Google Scholar
  28. 28.
    Resnick D, Kransdorf MJ. Bone and joint imaging. 3rd ed. Philadelphia: Elsevier Saunders; 2005.Google Scholar
  29. 29.
    Dickman CA, Mamourian A, Sonntag VKH, Drayer BP. Magnetic resonance imaging of the transverse atlantal ligament for the evaluation of atlantoaxial instability. J Neurosurg. 1991;75(2):221–7.Google Scholar
  30. 30.
    Tehranzadeh J, Ashikyan O, Dascalos J. Magnetic resonance imaging in early detection of rheumatoid arthritis. Semin Musculoskelet Radiol. 2003;07(2):079–94.Google Scholar
  31. 31.
    Karhu JO, Parkkola RK, Koskinen SK. Evaluation of flexion/extension of the upper cervical spine in patients with rheumatoid arthritis: an MRI study with a dedicated positioning device compared to conventional radiographs. Acta Radiol. 2005;46(1):55–66.Google Scholar
  32. 32.
    Passos-Cardoso A, da Silva N, Daher S, et al. Risk factors for development and progression of atlantoaxial subluxation in Korean patients with rheumatoid arthritis. Neurosurg Focus. 2015;45(4):540–6.Google Scholar
  33. 33.
    Matteson EL. Cervical spine disease in rheumatoid arthritis: how common a finding? How uncommon a problem? Arthritis Rheum. 2003;48(7):1775–8.Google Scholar
  34. 34.
    Wasserman BR, Moskovich R, Razi AE. Rheumatoid arthritis of the cervical spine—clinical considerations. Bull NYU Hosp Jt Dis. 2011;69(2):136–48.Google Scholar
  35. 35.
    Stiskal MA, Neuhold A, Szolar DH, et al. Rheumatoid arthritis of the craniocervical region by MR imaging: detection and characterization. Am J Roentgenol. 1995;165(3):585–92.Google Scholar
  36. 36.
    Del Grande M, Del Grande F, Carrino J, Bingham CO, Louie GH. Cervical spine involvement early in the course of rheumatoid arthritis. Semin Arthritis Rheum. 2014;43(6):738–44.Google Scholar
  37. 37.
    Larsson EM, Holtås S, Zygmunt S. Pre- and postoperative MR imaging of the craniocervical junction in rheumatoid arthritis. Am J Roentgenol. 1989;152(3):561–6.Google Scholar
  38. 38.
    Czerny C, Grampp S, Henk CB, Neuhold A, Stiskal M, Smolen J. Rheumatoid arthritis of the craniocervical region: assessment and characterization of inflammatory soft tissue proliferations with unenhanced and contrast-enhanced CT. Eur Radiol. 2000;10(9):1416–22.Google Scholar
  39. 39.
    Hirano K, Imagama S, Oishi Y, et al. Progression of cervical instabilities in patients with rheumatoid arthritis 5.7 years after their first lower limb arthroplasty. Mod Rheumatol. 2012;22(5):743–9.Google Scholar
  40. 40.
    Fujiwara K, Fujimoto M, Owaki H, et al. Cervical lesions related to the systemic progression in rheumatoid arthritis. Spine (Phila Pa 1976). 1998;23(19):2052–6.Google Scholar
  41. 41.
    Vu Nguyen H, Ludwig SC, Silber J, et al. Rheumatoid arthritis of the cervical spine. Spine J. 2004;4(3):329–34.Google Scholar
  42. 42.
    Zhang T, Pope J. Cervical spine involvement in rheumatoid arthritis over time: results from a meta-analysis. Arthritis Res Ther. 2015;17(1):148.Google Scholar
  43. 43.
    Ryu JI, Han MH, Cheong JH, et al. The effects of clinical factors and retro-odontoid soft tissue thickness on atlantoaxial instability in patients with rheumatoid arthritis. World Neurosurg. 2017;103:364–70.Google Scholar
  44. 44.
    Sono T, Onishi E, Matsushita M. Radiographic risk factors and surgical outcomes for retroodontoid pseudotumors. J Spinal Disord Tech. 2014;27(6):193–8.Google Scholar
  45. 45.
    Tanaka S, Nakada M, Hayashi Y, et al. Retro-odontoid pseudotumor without atlantoaxial subluxation. J Clin Neurosci. 2010;17(5):649–52.Google Scholar
  46. 46.
    Buttiens A, Vandevenne J, Van Cauter S. Retro-odontoid Pseudotumor in a patient with atlanto-occipital assimilation. J Belg Soc Radiol. 2018;102(1):62.Google Scholar
  47. 47.
    Yu SH, Choi HJ, Cho WH, Cha SH, Han IH. Retro-odontoid pseudotumor without atlantoaxial subluxation or rheumatic arthritis. Korean J Neurotrauma. 2016;12(2):180–4.Google Scholar
  48. 48.
    Crockard HA, Sett P, Geddes JF, Stevens JM, Kendall BE, Pringle JA. Damaged ligaments at the craniocervical junction presenting as an extradural tumour: a differential diagnosis in the elderly. J Neurol Neurosurg Psychiatry. 1991;54(9):817–21.Google Scholar
  49. 49.
    Patel NP, Wright NM, Choi WW, McBride DQ, Johnson JP. Forestier disease associated with a retroodontoid mass causing cervicomedullary compression. J Neurosurg. 2002;96(2 Suppl):190–6.Google Scholar
  50. 50.
    Zygmunt S, Säveland H, Brattström H, Ljunggren B, Larsson EM, Wollheim F. Reduction of rheumatoid periodontoid pannus following posterior occipito-cervical fusion visualised by magnetic resonance imaging. Br J Neurosurg. 1988;2(3):315–20.Google Scholar
  51. 51.
    Lagares A, Arrese I, Pascual B, Gòmez PA, Ramos A, Lobato RD. Pannus resolution after occipitocervical fusion in a non-rheumatoid atlanto-axial instability. Eur Spine J. 2006;15(3):366–9.Google Scholar
  52. 52.
    Grob D, Wursch R, Grauer W, Strurzenegger J, Dvorak J. Atlantoaxial fusion and retrodental pannus in rheumatoid arthritis. Spine J. 1997;22(14):1580–4.Google Scholar
  53. 53.
    Landi A, Marotta N, Morselli C, Marongiu A, Delfini R. Pannus regression after posterior decompression and occipito-cervical fixation in occipito-atlanto-axial instability due to rheumatoid arthritis: case report and literature review. Clin Neurol Neurosurg. 2013;115(2):111–6.Google Scholar
  54. 54.
    Yonezawa I, Okuda T, Won JH, et al. Retrodental mass in rheumatoid arthritis. J Spinal Disord Tech. 2012;26(2):1.Google Scholar
  55. 55.
    Bydon M, Macki M, Qadi M, et al. Regression of an atlantoaxial rheumatoid pannus following posterior instrumented fusion. Clin Neurol Neurosurg. 2015;137:28–33.Google Scholar
  56. 56.
    Chikuda H, Seichi A, Takeshita K, et al. Radiographic analysis of the cervical spine in patients with retro-odontoid pseudotumors. Spine J. 2009;34(3):E110–4.Google Scholar
  57. 57.
    Sinha P, Lee M-T, Panbehchi S, Saxena A, Pal D. Spontaneous regression of retro-odontoid post traumatic cicatrix following occipitocervical fixation. J Craniovertebr Junction Spine. 2017;8(3):278–82.Google Scholar
  58. 58.
    Klineberg E, Bui T, Schlenk R, Lieberman I. Retro-odontoid calcium pyrophosphate dehydrate deposition: surgical management and review of the literature. Evid Based Spine Care J. 2014;5(1):63–9.Google Scholar
  59. 59.
    Rousselin B, Helenon O, Zingraff J, et al. Pseudotumor of the craniocervical junction during long-term hemodialysis. Arthritis Rheum. 1990;33(10):1567–73.Google Scholar
  60. 60.
    Hatakeyama A, Fujinaga H, Togo T, et al. Remarkable improvement of activity by CAPD in a hemodialysis patient with a pseudotumor of the craniocervical junction. Adv Perit Dial. 1992;8:116–9.Google Scholar
  61. 61.
    Mulleman D, Flipo R-M, Assaker R, et al. Primary amyloidoma of the axis and acute spinal cord compression: a case report. Eur Spine J. 2004;13(3):244–8.Google Scholar
  62. 62.
    Kleinman GM, Dagi TF, Poletti CE. Villonodular synovitis in the spinal canal. J Neurosurg. 1980;52:846–8.Google Scholar
  63. 63.
    Finn MA, McCall TD, Schmidt MH. Pigmented villonodular synovitis associated with pathological fracture of the odontoid and atlantoaxial instability. J Neurosurg Spine. 2007;7(2):248–53.Google Scholar
  64. 64.
    Graham EJ, Kuklo TR, Kyriakos M, Rubin DA, Riew KD. Invasive pigmented villonodular synovitis of the atlantoaxial joint: a case report. J Bone Joint Surg Am. 2002;84-A(10):1856–60.Google Scholar
  65. 65.
    Blacksin MF, Avagliano P. Computed tomographic and magnetic resonance imaging of chronic odontoid fractures. Spine J. 1999;24(2):158–61 discussion 162.Google Scholar
  66. 66.
    Soon WC, Thanabalasundaram G, Thant KZ, Ogbonnaya ES, Harrisson SE. Obstructive hydrocephalus secondary to odontoid pannus: case report and review of literature. J Surg Case Rep. 2018;2018(4):rjy049.Google Scholar
  67. 67.
    Ohnishi Y, Iwatsuki K, Taketsuna S, Ninomiya K, Yoshimine T. Retro-odontoid synovial cyst resected via an anterolateral approach without fusion. Eur Spine J. 2015;24:508–13.Google Scholar
  68. 68.
    Badami JP, Hinck VC. Symptomatic deposition of epidural fat in a morbidly obese woman. Am J Neuroradiol. 1982;3(6):664–5.Google Scholar
  69. 69.
    Beatty RM, Winston KR. Spontaneous cervical epidural hematoma. J Neurosurg. 1984;61(1):143–8.Google Scholar
  70. 70.
    Haykal HA, Wang AM, Zamani AA, Rumbaugh CL. Computed tomography of spontaneous acute cervical epidural hematoma. J Comput Assist Tomogr. 1984;8(2):229–31.Google Scholar
  71. 71.
    Abiola R, Rubery P, Mesfin A. Ossification of the posterior longitudinal ligament: etiology, diagnosis, and outcomes of nonoperative and operative management. Glob Spine J. 2016;6(2):195–204.Google Scholar
  72. 72.
    Okada K, Kozo S, Abe E. Hypertrophic dens resulting in cervical myelopathy. Spine. 2000;25(10):1303–7.Google Scholar
  73. 73.
    Shidham V, Chivukula M, Basir Z, Shidham G. Evaluation of crystals in formalin-fixed, paraffin-embedded tissue sections for the differential diagnosis of pseudogout, gout, and tumoral calcinosis. Mod Pathol. 2001;14(8):806–10.Google Scholar
  74. 74.
    Leaney BJ, Calvert JM. Tophaceous gout producing spinal cord compression. Case report. J Neurosurg. 1983;58(4):580–2.Google Scholar
  75. 75.
    Sekijima Y, Yoshida T, Ikeda SI. CPPD crystal deposition disease of the cervical spine: a common cause of acute neck pain encountered in the neurology department. J Neurol Sci. 2010;296(1–2):79–82.Google Scholar
  76. 76.
    Baysal T, Baysal O, Kutlu R, Karaman I, Mizrak B. The crowned dens syndrome: a rare form of calcium pyrophosphate deposition disease. Eur Radiol. 2000;10(6):1003–5.Google Scholar
  77. 77.
    Lee GS, Kim RS, Park HK, Chang JC. Crowned dens syndrome: a case report and review of the literature. Korean J Spine. 2014;11(1):15.Google Scholar
  78. 78.
    Ledingham D, Cappelen-Smith C, Cordato D. Crowned dens syndrome. Pract Neurol. 2018;18(1):57–9.Google Scholar
  79. 79.
    Parmar HA, Sitoh YY, Tan KK, Teo J, Ibet SM, Hui F. MR imaging features of pigmented villonodular synovitis of the cervical spine. Am J Neuroradiol. 2004;25(1):146–9.Google Scholar
  80. 80.
    Roguski M, Safain MG, Zerris VA, et al. Pigmented villonodular synovitis of the thoracic spine. J Clin Neurosci. 2014;21(10):1679–85.Google Scholar
  81. 81.
    Malca SA, Roche PH, Pellet W, Combalbert A. Crowned dens syndrome: a manifestation of hydroxy-apatite rheumatism. Acta Neurochir. 1995;135(3–4):126–30.Google Scholar
  82. 82.
    Wada K, Murata Y, Kato Y. Surgical outcome for hemodialysis-related upper cervical lesions. Asian Spine J. 2015;9(5):699–704.Google Scholar
  83. 83.
    Lavrador JP, Oliveira E, Gil N, Francisco AF, Livraghi S. C1-C2 pigmented villonodular synovitis and clear cell carcinoma: unexpected presentation of a rare disease and a review of the literature. Eur Spine J. 2014;24(S4):465–71.Google Scholar
  84. 84.
    Julien TD, Frankel B, Traynelis VC, Ryken TC. Evidence-based analysis of odontoid fracture management. Neurosurg Focus. 2000;8(6):1–6.Google Scholar
  85. 85.
    Young WF, Boyko O. Magnetic resonance imaging confirmation of resolution of periodontoid pannus formation following C1/C2 posterior transarticular screw fixation. J Clin Neurosci. 2002;9(4):434–6.Google Scholar
  86. 86.
    Hamard M, Martin SP, Boudabbous S. Retroodontoid pseudotumor related to development of myelopathy secondary to atlantoaxial instability on os odontoideum. Case Rep Radiol. 2018;2018:1–10.Google Scholar
  87. 87.
    Desai MA, Peterson JJ, Garner HW, Kransdorf MJ. Clinical utility of dual-energy CT for evaluation of tophaceous gout. Radiographics. 2011;31(5):1365–75.Google Scholar
  88. 88.
    Kakutani K, Doita M, Yoshikawa M, et al. C1 laminectomy for retro-odontoid pseudotumor without atlantoaxial subluxation: review of seven consecutive cases. Eur Spine J. 2013;22(5):1119–26.Google Scholar
  89. 89.
    Chang H, Park J-B, Kim K-W. Synovial cyst of the transverse ligament of the atlas in a patient with os odontoideum and atlantoaxial instability. Spine J. 2000;25(6):741–4.Google Scholar
  90. 90.
    Resnick D, Guerra J, Robinson C, Vint V. Association of diffuse idiopathic skeletal hyperostosis (DISH) and calcification and ossification of the posterior longitudinal ligament. Am J Roentgenol. 1978;131(6):1049–53.Google Scholar
  91. 91.
    Min J-H, Jang J-S, Lee S-H. Significance of the double-layer and single-layer signs in the ossification of the posterior longitudinal ligament of the cervical spine. J Neurosurg Spine. 2007;6(4):309–12.Google Scholar

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© ISS 2019

Authors and Affiliations

  1. 1.Department of Radiology, Division of Musculoskeletal Imaging and InterventionBrigham and Women’s HospitalBostonUSA
  2. 2.Harvard Medical SchoolBostonUSA
  3. 3.Division of Rheumatology, Immunology and Allergy, Department of MedicineBrigham and Women’s HospitalBostonUSA

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