Bone & joints
Other nonneoplastic
Synovial cysts
Author: Vijay Shankar, M.D.
Last author update: 1 December 2018
Last staff update: 29 December 2020
Copyright: 2002-2025, PathologyOutlines.com, Inc.
PubMed Search: synovial cyst [title]
Table of Contents
Definition / general | Terminology | Clinical features | Diagrams / tables | Radiology images | Case reports | Treatment | Clinical images | Radiology images | Microscopic (histologic) description | Microscopic (histologic) imagesCite this page: Shankar V. Synovial cysts. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/jointssynovialcysts.html. Accessed January 8th, 2025.
Definition / general
- Herniation of synovium through joint capsule, usually in joint of extremities
- May bleed and become a mass-like lesion
Terminology
- Baker cyst: also called popliteal cyst; synovial cyst in popliteal space
- Cutaneous metaplastic synovial cyst: lined by metaplastic synovial tissue; may be due to local trauma
- Spinal synovial cyst: cyst in spinal joint
Clinical features
- Baker cyst: due to herniation of synovial membrane through posterior joint capsule or escape of joint fluid from bursae; associated with degenerative joint disease, neuropathic arthropathy, rheumatoid arthritis
- Spinal synovial cyst:
- Soft tissue mass located extradurally along medial border of degenerated facet joint
- Usually at L4-5, rarely in cervical or thoracic spine
- Filled with clear or xanthochromic fluid
- Causes back and radicular pain
- Rarely results in cauda equina syndrome (Pain Physician 2012;15:435)
Diagrams / tables
Images hosted on other servers:
Baker cysts
Radiology images
Images hosted on other servers:
Spinal synovial cyst
Case reports
- 14 year old girl with synovial cyst of thoracic spine (Arq Neuropsiquiatr 2007;65:838)
- 44 year old woman with lower extremity pain, swelling and Baker cyst (Int J Emerg Med 2010;3:469)
- 45 year old man with rheumatoid arthritis, pain in calf and Baker cyst (N Engl J Med 2009;361:1098)
- 51 year old woman with cutaneous metaplastic synovial cyst of first metatarsal head area (Ann Dermatol 2011;23:S165)
- 63 year old woman with intradural invasion of lumbar synovial cyst (Neurol Med Chir (Tokyo) 2012;52:234)
- 71 year man with synovial cyst of thoracic spine (BMJ Case Rep 2009 Feb 16;2009)
- 72 year old woman with hemorrhagic lumbar synovial cyst (J Korean Neurosurg Soc 2012;52:567)
- 84 year old man with cervical brachyalgia and spinal synovial cyst (Eur Spine J 2010;19:S100)
Treatment
- Baker cyst: treat cause of excess fluid, sclerotherapy (Pain Physician 2008;11:375)
- Cutaneous metaplastic synovial cyst: surgical excision; recurrence is rare
Clinical images
Images hosted on other servers:
Baker cysts
Cutaneous metaplastic synovial cyst
Radiology images
Images hosted on other servers:
MRI of Baker cyst
Microscopic (histologic) description
- Baker cyst: lined by synovium, may have cartilage in cyst wall; palisading histiocytes and fibrinoid necrosis, similar to rheumatoid pericarditis and rheumatoid nodules
- Cutaneous metaplastic synovial cyst: cystic structure with papillary projections lined by epithelium resembling synovium
Microscopic (histologic) images
Images hosted on other servers:
Cutaneous metaplastic synovial cyst with numerous villous-like structures; vimentin+ CD34- CD68-
Hemorrhagic spinal synovial cyst with thin fibrous wall
