Elias Pretorius. Soft tissue mass of the hip 46 year old male patient : Painless swelling in his right thigh ⁻ Insidious onset ⁻ Gradual enlargement over.

CASE PRESENTATIONElias Pretorius

Soft tissue mass of the hip46 year old male patient :Painless swelling in his right thigh

⁻ Insidious onset ⁻ Gradual enlargement over two years⁻ Painless ⁻ not causing any functional impairment

No significant medical history, no chronic medicationRVD Non-reactive

No history of traumaNo Surgical history

Smoker, consumes moderate amounts of EtOH

Examination

Examined by the Orthopedic Surgeon : Generally good condition Normal systemic examination recorded

MASS : Obvious ovoid mass visible below the right buttock Extending to postero-lateral thigh 10x10cm Soft Fluctuant, movable Non-tender Non-pulsatile No Inflammatory features

Examination

Orthopedic Examination Normal gait Normal ROM right knee and hip joint Right leg NV intact

No other masses reported/found

Investigations

Bloods - normal CXR US

Well defined cystic mass containing echogenic material No vascularity within

US guided Aspirate Serous, straw colored material Cytology: inconclusive MCS: gram stain negative,

culture negative(incl TB) MRI right femur

Follow up

Pig tail - drainage – enlarged to full size again

1. Inflammatory

2. Infective

3. Malignancy

Differential diagnosis?

Excision Biopsy

Intra-op Large cystic mass resected filled with a cloudy yellowish fluid Small communicating tractus with the right hip joint

Histology Cystic structure lined by ulcerated synovium Cyst wall comprised of fibroconnective tissue No features of tuberculosis or malignancy

Dx: Right thigh synovial cyst

Synovial cysts (myxoid-, mucous cyst)

Peri-articular fluid collections Leakage of joint fluid into the soft

tissue lined by synovial membrane May or may not communicate with

the adjacent joint Common in the extremities

The first published reports of a synovial cyst :

1840, Irish surgeon, Adams

Recorded observations on synovial cysts resulting in the common eponym Baker cysts, for popliteal cysts :

1877, William Baker

Etiology

Any long-standing or large effusion of any cause

Three aetiological factors: Traumatic Degenerative

osteoarthrosis Inflammatory conditions

Rheumatoid arthritis Seronegative spondyloarthropathies Crystal deposition diseases

Clinical features

Manifests as a peri-articular swelling Any age / gender Usually asymptomatic Complications :

Pain or limitation of joint mobility Compression of the neighbouring neurovasular

structures Acute rupture occur infrequently which may

dissect into adjacent soft tissues Secondary infection and abscess formation

Colesante et al(2006)

Frequent sites: Knee (Popliteal fossa most common) Shoulder Wrist Fingers feet

Uncommon locations : Elbows Ankles Hips Apophyseal joints of the spine

Synovial cyst of the hip

Extremely rare Originates :

True articular synovial herniation without bursal involvement

may develop from bursal cavities Ilioinguinal bursa (largest synovial bursa of the

hip)

The presence of hip joint abnormalities favours a joint synovial cyst

Pathophysiology

Synovitis

Formation of reactive inflammatory fluid

Raised intra-articular pressure

Formation of synovial cysts constitutes an effective decompressive mechanism

Unilateral egress of fluid from the inflammed joint

Detrimental to synovial perfusion

May cause joint instability

Pathophysiology

No communication with the hip joint

Hypertrophic/villous proliferation of bursal lining

Fluid overproduction

Isolated bursal enlargement

Bursitis

77 year old male patient with a synovial cyst

Adventitial cyst

Adventitial cyst

Close proximity to synovial joint Exact aetiology of formation remains

unclear Interesting theory:

Develops from synovial rests sequestrated in the vessel wall during development

Communication between the cyst and joint can be demonstrated (knee)

Synovial Pseudocysts

Ganglion Myxomatous degeneration of the fibrous

tissue structures Do not have a lining of synovial cells at

histologic analysis Adjacent to a tendon sheath or joint

capsule which contains mucoid fluid

Therefore, most ganglia are pseudocysts

Exact aetiology unknown Traumatic Degenerative Inflammatory

Around hip, associated with unusual/ various clinical presentations

Mimics : Inguinal hernia Pulsitile groin mass/ aneurysm Lymphnodes / mets Synovial Cysts

Ganglion cyst of the hip

Image of Ganglion

Geodes / Subchondral cyst are juxta-articular bone cysts that lack a

true epithelial lining pseudocyst Synovial fluid forced into bone Association with DJD

Synovial Pseudocysts

Imaging of Synovial Cysts

Plain Radiographs Non specific

Joint evaluation Site of lesion Underlying bone involvement Calcifications

Imaging

Arthrography Cyst communication Filling of a soft tissue mass adjacent to

the supraacetabular bone Internal derangement of the joint

Labral tears Debris

Imaging

Ultrasound As sensitive at arthrography for true

synovial cysts Considering the deep location of the hip,

MRI is more effective than US in the assessment of synovial cysts

Imaging

Computed Tomography scan Peri-articular Connection? Cystic characteristics No enhancement

Imaging

MRI Best imaging modality Optimal delineation of the extent Confirm the synovial nature of the cyst

Communication with the hip joint or an adjacent bursitis

Assessment of the associated causative disorder

Characteristics intermediate signal intensity on T1WI High signal intensity on T2WI Ring enhancing synovial lining

Soft tissue mass : synovial cyst Treatment

May spontaneously disappear, thus expectant management is appropriate

When symptomatic Aspiration and injection of steroids

optimal aspiration occurs at the base of the ganglionsingle vs multiple punctures were compared = equal

Surgical removal – entire cyst should be removed including attachments to joint capsule and underlying ligaments -10% recur

Conclusion

Synovial cysts of the hip is rare Typically due to RA or DJD May mimic different disorders and

should be kept in mind in the differential diagnosis of unusual groin pain, radicular pain and peripheral vascular disorders

References

Dr G van Staden, Orthopedic Surgeon – Kimberley Hospital Complex

D Patkar, J Shah, S Prasad Giant rheumatoid synovial cyst of the hip joint: diagnosed by MRI 1999 vol.45:issue 4: 118-119

Wang LF, Xu SZ, Lin XJ. Zhongguo Gu Shang A review of diagnosis and causes of synovial cyst of the hip joint 2010 Apr;23(4):271-4.

HW Bolhuis, Van der Werf TS, Tjabbes T Giant synovial cyst of the hip joint presenting with femoral vein compression Neth J Surg 1990 Jun;42(3)88-91

Vo P, Wright T, Hayden F, Dell P Chidgey evaluating dorsal wrist pain: MRI diagnosis of occult dorsal wrist ganglion J Hand Surg Am. 1995;20(4):667

UpToDate Apley’s System of Orthopedics and fractures