MSK Radiology Interesting Case Presentation

Sitt Ching Man Jacqueline

10 Feb 2015

Patient 1: Young Female athelete

• Triathlon runner

• Complains of chronic pain of the medial joint

line of the knee during training

Patellofemoral disease

• Three well-defined entities:

– Objective patellar instability (OPI)

• at least one episode of true patellar dislocation, and

• at least one anatomical abnormality on imaging

– trochlear dysplasia / patellar alta / patellar tilt / Tibial-tuberosity trochlear groove abnormality

– Potential patellar instability (PPI)

• Subjective patellar pain +/- instability

• Same anatomical abnormalities as OPI

• No true patellar dislocation

– Patellar pain syndrome (PPS)

• No major morphological abnormality on imaging

• Symptoms include patellar pain, reflex buckling, pseudolocking

Patellar tendon-lateral femoral condyle friction syndrome (PLFFS) • Patellofemoral friction syndrome (PLS)

• More in females (~60-70%)

• On the border between patellar pain syndrome (PPS) and potential

patellar instability

• Associated with minor morphologic and soft tissue abnormalities

– recognised as a marker of patellofemoral malalignment and

maltracking

– higher patellar-height index and tibial-tuberosity to trochlear groove

distance

PATELLA ALTA

Up to 25% of patients with acute patellar dislocation have a high riding patella depicted on MR.

Patellar height ratio (PHR). The length of the patellar tendon (A) is measured posteriorly from the patellar apex to its attachment to the tibial tuberosity and is divided by the longest superoinferior diameter of the patella (B). A ratio of A/B >1.3 indicates patellar alta, as in this example (PHR of 1.33).

LATERALIZATION OF THE TIBIAL TUBEROSITY

The distance from the deepest point of the trochlea (blue) to the middle of the tibial tubercle (green) is measured, by using the posterior plane of the condyles as the reference line (red). A distance of <15mm is normal, 15-20mm is considered borderline, while a distance of >20mm indicates marked lateralization of the tuberosity, as in this example.

Patellofemoral Friction Syndrome

• Specific MRI findings: Oedema in the superolateral portion of the

infrapatellar fat pad

• The patellar cartilage can be morphologically entirely normal

• Can be associated with high T2 signal of medial patellar facet

– or in early cases high “bulk average T2 relaxation time” on “T2

mapping”

– Suggests early patellofemoral cartilage damage

Subhawong Ty K, Thakkar RS, Padua A, et al. Patellofemoral friction syndrome: Magnetic Resonance Imaging Correlation of Morphologic and T2 cartilage imaging. J Comput Assist Tomogr 2014; 38: 308-312.

Patient 2: 19/M Korean

• Incidental note of a synovial mass in left knee

on MR (?routine body check)

• Active basket ball player

• No symptoms otherwise

• Physical examination: Unremarkable

Focal Nodular Synovitis of knee

• Benign localised synovial proliferation

• Found predominantly in tendon sheaths or joints of fingers

and toes; Rarely involve large joints eg knee and ankles

– Infrapatellar fat pad > suprapatellar pouch

– Less common: intercondylar notch, PCL

• Symptoms and signs: pain, joint swelling / fullness, joint

line tenderness, restricted ROM, locking of knee, palpable

mass

Focal nodular synovitis of knee

• MR appearance variable:

– Iso to hyperintense relative to skeletal muscle on T1

– Variable signal on T2

– Circular regions of intermixed low signal = hemosiderin

deposits

• Presence of pedicle: torsion acute pain

(Huang GS, Lee CH, Chan WP, et al. Localised nodular synovitis of the knee: MR imaging appearance and clinical

correlates in 21 patients. AJR:181, 2003: 539-543.)

Focal nodular synovitis vs PVNS

• Shares histologic features with PVNS

Features Focal nodular synovitis PVNS

Abundance of hemosiderin

+ +++

Diffuse frond-like projections of synovium

- +

Contour or lesion Smooth More irregular

Hemorrhagic joint effusion

- +

Growth pattern Grows outwards and becomes pedunculated

Growing synovial mass constricts the joint

Treatment option Complete excision with negligible recurrence

Extensive synovectomy because of its frequent recurrence

For comparison: Nodular PVNS

Nodular PVNS

Patient 3: 56/F Housewife

• C/o Right iliac fossa pain for 3 days

• Physical examination: Fever, Tachycardia,

tenderness +/- guarding at right iliac fossa

• WBC elevated

• ? Acute appendicitis

Follow-up 5 days later

Vacuum phenomenon

– commonly seen in osteoporotic vertebral

fractures

– Nitrogen gas collections within area of

negative pressure created by distraction of

tissues in intervertebral discs (generated

by “opening-closing” mechanism during

the collapse of the vertebral body)

– Usually band-like with peripheral sclerosis

Vacuum phenomenon

• Rare in spinal infection and metastases

– Bone destruction and erosion instead of real fracture

two or more fracture fragments the opening-

closing mechanism does not occur

– Active tissue inflammation continuous and

dynamic tissue expansion fluid accumulation and

tissue swelling Positive pressure generated

Intervertebral disc gas in spinal infection

• Gas generated under high pressure

• Atypical distribution of gas: uneven, “bubble-

like”, widely distributed in peripheral tissues

• Depicted on CT instead of plain radiographs

• Probably related to gas-forming organisms

– Associations with Clostridia, Brucellosis, TB and

peptococcus had been reported

Feng SW, Chang MC, Wu HT, et al. Are intravertebral vacuum phenomena benign lesions? Eur Spine J (2011) 20:1341-1348

Patient 4: 56/F Housewife

• End stage renal failure of unknown cause

• Renal transplant in 1984, failed graft

• CAPD since 2007

• C/O LBP for 6 months, progressive severity

• No limb weakness / sphincter disturbance

• PE: unremarkable neurological exam

CT LS Spine

CT findings

• Multiple osteolytic foci involving vertebral

bodies, pedicles and posterior elements

• Moderate to severe spinal canal stenosis at

L1, due to extraosseous tumoral expansion

• Suggested MRI and CT guided biopsy

MRI findings

• Large vertebral lesion involving left posterior body,

pedicle and posterior element

• Significant extra-osseous extension into spinal canal

• Severe displacement and compression of conus

medullaris (with mild oedema) and cauda equina

• Also foraminal narrowing at left T12/L1 and L1/L2 but

no exiting root compression

Differential diagnoses?

• Amyloidosis

• Myeloma

• Metastases

• Brown tumour

CT guided biopsy

Diagnosis: Brown Tumour

• Previous MIBI scan: parathyroid hyperplasia

• PTH 109, patient already put on medical treatment

(Cinacelet)

• Patient was reluctant for parathyroidectomy

• Referred to neurosurgeons: Option of laminectomy,

decompression and posterior spinal fusion discussed

but declined by patient

Brown tumour in the spine

• Very rare

• Benign tumour associated with hyperparathyroidism

(in theory primary > secondary)

• Usually associated with chronic renal disease

• Presentation:

– insidious with progressive cord compression

– Acute with pathological fractures

Brown tumour of the spine

• X Rays, CT / MR: lytic solitary or multifocal sharply

demarcated expansile lesions

• Bone scan: MDP avid, mimic metastases

• Should be considered as one of the ddx in ESRF

patients (in context of tertiary hyperPTH)

• Diagnosis by exclusion; CT guided biopsy helpful for

discrimination

Kampschreur LM, Hoogeveen EK, op den Akker JW, et al. A hemodialysis patient with back pain: brown tumour as a cause of spinal cord compression under cinacalcet therapy. NDT Plus (2010) 3:291-295

Treatment options

• Like other brown tumours, may resolve 1-2 years

after subtotal parathyroidectomy

• Can occur even when patient is on medical

treatment (previous case reports)

• Urgent decompression in acute presentations

with neurological deficits (but high operative

risks) Mak KC, Wong YW, Luk KDK. Spinal cord compression secondary to brown tumour in a patient on long-term hemodialysis: a case report. Journal of Orthopedic Surgery 2009; 17(1):90-5.

Summary

• Brown tumour of the spine as a rare differential diagnosis

with lytic vertebral tumour causing spinal cord / cauda

equina compression in patients with ESRF

• Correlation with features of tertiary hyperparathyroidism

• Diagnosis by exclusion; biopsy with histological

examination useful for discrimination

• Aim of treatment: control PTH level by subtotal

parathyroidectomy

Thank you!