Paediatric Orthopaedic topic. Bone cysts in Children

1. BONE CYSTS IN
CHILDREN
Seneeth Peramuna

2. MAIN CONCERNS
• Unicameral / Simple Bone cysts
• Aneurysmal Bone Cysts
• Telangiectatic Osteosarcoma
• Fibrous Dysplasia
• Nonossifying fibroma
• Langerhans cell Histiocytosis
• Osteoid Osteoma

3. UNICAMERAL BONE CYSTS / SIMPLE BONE CYSTS
• Unicameral = Single Chamber
• Male : Female ratio = 3:1
• Usually seen in 1st decade of life
• Location
• At Metaphysis, near to physis and develops towards diaphysis
• Proximal humerus, proximal femur, distal tibia, ilium, calcaneus,
and occasionally metacarpals, phalanges, or distal radius

4. UNICAMERAL BONE CYSTS
• Characteristic sign = Fallen leaf sign
(pathologic fracture with fallen cortical fragment in base of
empty cyst is pathognomonic)
• Central, lytic , well-demarcated metaphyseal lesion (2-3%
cross physis)
• Cystic expansion with symmetric thinning of cortices

5. UNICAMERAL BONE CYSTS - FUNCTIONAL
CLASSIFICATION
• Active
• if cyst is adjacent to the physis
• Latent
• if normal bone separates cyst from
physis

6. UNICAMERAL BONE CYSTS - TREATMENT OPTIONS
1. Immobilization alone
2. Aspiration +/- Methylprednisolone injection for
active lesions
3. Curettage and Bone grafting
- Avoid active lesions as it can cause growth arrest.

7. UNICAMERAL BONE CYSTS
Would the cysts tend to heal
spontaneously
post fracture?
No
Fracture healing usually does not lead to cyst resolution,
how ever fracture will heal rapidly as an abundant callus is
formed

8. UNICAMERAL BONE CYSTS - PROGNOSIS
•When reaching skeletal
maturity UBC will reduce size
and heal
•Need to follow-up due to
Fracture risk and growth arrest

9. ANEURYSMAL BONE CYSTS
• Benign, expansile, vascular lesions that usually
involve the metaphysis of long bones but identified
throughout the skeleton.
• most common benign aggressive tumor in the
pediatric population.
• There is a female preponderance, and 80% of these lesions
occur in the second decade.

10. ANEURYSMAL BONE CYSTS
Commonly in the humerus, femur and tibia.
Spine is involved in 20% of cases and can
cause neurological compromise that may even
be acute due to vertebral collapse

11. ANEURYSMAL BONE CYSTS
30% are secondary!
forming a cystic part of an
osteosarcoma, giant cell tumour,
osteoblastoma or chondroblastoma

12. ANEURYSMAL BONE CYSTS
• It was thought to be caused by intraosseous hemorrhage
because of venous stasis and bone resorption due to the
activation of osteoclasts.
However, this is no longer the accepted theory for primary
ABC. Approximately 70% of primary ABC lesions are associated
with recurrent chromosomal translocations causing gene
fusions between ubiquitin specific peptidase 6 (USP6) and
multiple genes.

13. ANEURYSMAL BONE CYSTS - X RAY APPEARANCE
• An expansile, often eccentric, metaphyseal lesion.
• Depending on the active nature of the cyst, the cortex
is thinned or the cyst is lined by a thin shell of
subperiosteal new bone formation.

14. ANEURYSMAL BONE CYSTS
Inactive: The periosteal ‘shell’ is intact and has
sclerotic
margins,
Active: Incomplete periosteal shell with defined
border,
Aggressive: Absent periosteal shell or evidence of
bone
formation

15. ANEURYSMAL BONE CYSTS - MRI
APPEARANCE
MRI demonstrates ‘fluid–fluid’ levels and contrast
enhancing walls of the cyst.
The fluid–fluid level is not a pathognomonic feature as it
is also seen in telangiectatic osteosarcoma, giant cell
tumours and simple bone cysts following fractures.

16. ANEURYSMAL BONE CYST - TREATMENT
OPTIONS
• Curettage and bone grafting.
• Traditional choice but there is a high rate of recurrence.
• Combining curettage with high-speed burring of the surrounding bone
has been reported to result in healing rates of 90%
• Cryotherapy and sclerotherapy.
• Arterial embolization may be used as an adjunct to surgery or in areas where surgical
management is challenging, e.g. the pelvis and spine
• En-bloc resection may be considered where the bone is expendable, e.g. the rib and
fibula

17. TELANGIECTATIC OSTEOSARCOMA
• Rare, malignant, high-grade osteosarcomas
• Most commonly in the proximal humerus,
the femur, and proximal tibia
• Patients typically present between the ages
of 5 and 25 with regional pain and swelling

18. TELANGIECTATIC OSTEOSARCOMA - PRESENTATION
• Symptoms - pain
• similar in ABC in presentation (must differentiate)
• 25% present with pathologic fracture
• Physical exam
• soft tissue swelling
• local tenderness

19. TELANGIECTATIC OSTEOSARCOMA - IMAGING
• Radiographs
• lytic, destructive, and expansile lesion; entire cortex
may be compromised
• Bone scan
• shows increased uptake
• MRI
• indicated in all cases to determine soft tissue
involvement
• findings
• fluid-fluid levels
• extensive edema in surrounding tissue

20. TELANGIECTATIC OSTEOSARCOMA – MAIN DD ABC
• diagnosis needs to be confirmed by an experienced
musculoskeletal pathologist
• differentiating ABC from telangietic osteosarcoma
is difficult and critical
• both have similar radiographic appearance
• both have large blood filled spaces
• both have similar location (proximal humerus,
proximal femur, distal femur, proximal tibia)

21. TELANGIECTATIC OSTEOSARCOMA – TREATMENT
• Operative , all most all the time
• Limb salvage possible 90% of the time
• neoadjuvant chemotherapy, limb salvage resection, followed by adjuvant
chemotherapy
• preoperative chemotherapy given for 8-12 weeks followed by maintenance
chemotherapy for 6-12 months after surgical resection
• doxorubicin/cisplatin/methotrexate/ifosamide
• 98% necrosis with chemo is good prognostic sign

22. TELANGIECTATIC OSTEOSARCOMA – COMPLICATIONS AND
PROGNOSIS
• Local recurrence uncommon (~5%)
• associated with poor prognosis
• Prognosis - more chemo-sensitive but same survival as intramedullary
osteosarcoma
• 5 year survival with tumor localized to an extremity is ~70%
• 5 year survival with metastases is ~20%

23. FIBROUS DYSPLASIA
A benign condition that is characterized by expansile fibro-osseous tissue in one or more
bones.
The bone has a disordered woven appearance, as opposed to adult lamellar bone.
Classification
• Monostotic: Only one bone involved.
• Polyostotic: Several areas of the skeleton may be affected. Commonly, the metaphyseal
and diaphyseal regions of the long bones, skull and mandible are involved

24. FIBROUS DYSPLASIA - PATHOPHYSIOLOGY
There is thus a failure of maturation of immature woven
bone to lamellar bone
The woven bone fails to adapt to mechanical stress (the
trabeculae are inappropriately orientated and encased in
fibrous tissue) and does not mineralize appropriately
usually present with pain, deformity or a pathological
fracture. Bone pain is caused by fatigue fractures in the
pathological bone.

25. FIBROUS DYSPLASIA – SHEPHERDS’S CROOK SIGN & GROUND GLASS APPEARANCE.
Deformity seen in the polyostotic form,
commonly involving the proximal femur
‘shepherd’s crook sign’, tibia and
humerus.
spreading flame’ appearance
in the ground-glass’ quality

26. FIBROUS DYSPLASIA – TREATMENT OPTIONS
1. Observation - mainstay of treatment in asymptomatic lesions.
2.Bisphosphonates - to treat bone pain and reported to improve cortical thickness in pathological bone.
3.Operative management - when progressive deformity or fracture occurs or is anticipated, typically with the
more severe polyostotic involvement.
• Curettage - This has a relatively high rate of failure due to recurrence. The choice of bone graft is an essential
part
• Stabilization - If the deformity is diaphyseal, intramedullary stabilization using rods.

27. NON OSSIFYING FIBROMA
• Benign fibrogenic lesion that result from dysfunctional ossification
• Most commonly found in the metaphysis of long bones.
• Typically present between the ages of 5 and 15 with an
asymptomatic lesion
• Discovered incidentally on radiographs.

28. NON OSSIFYING FIBROMA
• 30-40% of skeletally immature children
• more common in males (2:1)
• 80% in lower extremity
• distal femur > proximal tibia > distal tibia
• uncommon in proximal femur, proximal humerus

29. NON OSSIFYING FIBROMA
• Characteristic metaphyseal eccentric "bubbly" lytic lesion
surrounded by sclerotic rim
• cortex may be expanded and thin
• length > width
• as bone grows lesion migrates to diaphysis
• lesions can enlarge up to 1-7cm

30. NON OSSIFYING FIBROMA - MECHANISM
• Related to dysfunctional ossification
• Abnormal osteoclastic resorption at the subperiosteal level during remodeling of
the metaphysis
• Associated conditions - Jaffe-Campanacci syndrome, congenital syndrome of
multiple non-ossifying fibromas
• cafe au lait pigmentation
• mental retardation
• heart, eyes, gonads involved neurofibromatosis

31. NON OSSIFYING FIBROMA – TREATMENT OPTIONS
• Observation
• first line of treatment
• most lesions resolve spontaneously and progressively reossify as child
enters 2nd and 3rd decade of life
• curettage and bone grafting
• symptomatic and large lesion (> 50-75% cortical involvement)
• increased risk of fracture shown on quantitative CT

32. NON OSSIFYING FIBROMA – COMPLICATIONS AND
PROGNOSIS
• Pathologic fracture incidence 90% occur in the lower extremity 50%
occur in the distal tibia
• Casting is the main stay of treatment
• Usually spontaneously resolves
• No malignant or metastatic potential

33. LANGERHANS CELL HISTIOCYTOSIS
• Is a rare group of disorders without a well-understood
etiology.
• Comprised of 3 different clinical syndromes that
demonstrate indistinguishable histology.
• Eosinophilic Granulomas are self-limiting benign
histiocytic lesions that can occur in isolation
• Hand-Schuller-Christian (HSC) disease – Visceral
involvement
• Letterer-Siwe disease (LSD) - fatal in early childhood.

34. LANGERHANS CELL HISTIOCYTOSIS
• Eosinophilic granuloma
• commonly presents in the skull, ribs, clavicle, scapula, mandible
• isolated lesions of the spine (thoracic most common)
• can also occur in diaphyseal regions of long bones and the pelvis
• HSC
• multiple bony sites
• multiple lytic skull lesions
• visceral involvement of the lungs, spleen, liver, skin, lymph nodes
• Exophthalmos
• Diabetes Insipidus

35. LANGERHANS CELL HISTIOCYTOSIS - XRAY
• known as "the great mimicker" as it appears similar to many
lesions
• DD - includes osteomyelitis, leukemia, lymphoma, fibrous dysplasia,
or Ewing's sarcoma
• Diaphyseal lesions
• well defined intramedullary lytic or "punched-out" lesion
• cortex may be thinned, expanded, or destroyed
• may have periosteal reaction

36. LANGERHANS CELL HISTIOCYTOSIS – X RAY
• metaphyseal lesions extend up to but not
through the physis less central location than
diaphyseal lesions

37. LANGERHANS CELL HISTIOCYTOSIS – X RAY
• spinal lesions
• vertebra plana (flattened vertebrae) in spine
• increased kyphosis
• cranial involvement
• multiple "punched-out" lytic lesions

38. LANGERHANS CELL HISTIOCYTOSIS – TREATMENT
OPTIONS
• observation alone
• Bracing to prevent progressive kyphosis of the spine
• low dose irradiation (600-800 cGy)
• indicated for lesions in the spine that compromise stability,
neurologic status
• lesions not amenable to injection or open treatment
• chemotherapy
• diffuse HSC
• corticosteroid injection

39. LANGERHANS CELL HISTIOCYTOSIS – TREATMENT OPTIONS
• curettage and bone grafting indications for lesions
that endanger the articular surface or are a risk for
impending fractures
• spinal deformity correction
• progressive spine deformity refractory to
bracing

40. OSTEOID OSTEOMA
• Small, benign, osteogenic bone lesions commonly found in the
proximal femur.
• typically present between ages 5 and 25 with regional pain that is
worse at night and improves with NSAIDS..

41. OSTEOID OSTEOMA – PATHO ANATOMY
• nidus
• central nodule of woven bone and osteoid with
osteoblastic rimming
• reactive zone
• area of thickened bone and fibrovascular tissue
• characteristic lesion that is less than 1.5 cm in
diameter with a sclerotic margin and radiolucent
nidus

42. OSTEOID OSTEOMA – WHY PAIN?
• pain
• attributed to increased local concentration of prostaglandin E2 and COX1 & 2
expression
• increased number and size of unmyelinated nerve fibers within the nidus
• Character of pain
• constant and progressive
• worse at night and with drinking ETOH
• relieved by NSAIDS
• may be adjacent to joint and mimic arthritis
• hand lesions may present with painless swelling

43. OSTEOID OSTEOMA – TREATMENT OPTIONS
• Clinical observation and NSAID administration
• Percutaneous radiofrequency ablation
• done under CT guidance
• probe at 80-90 deg C for 6 minutes to produce a 1cm zone of
necrosis
• MR-guided high-intensity focused ultrasound (MR-HIFU
• Surgical resection with curettage

44. OSTEOID OSTEOMA – PROGNOSIS
• Pain from lesions usually resolves after an
average of 3 years
• The lesion spontaneously resolves in 5-7 years
• In the spine, early resection (within 18 months)
leads to resolution of scoliosis in young children
(<11years)

45. •Thank you