This document discusses various types of cystic bone lesions. It begins by defining what a cyst is and describing the general features of cystic lesions in bone. It then discusses four specific types of cystic bone lesions - solitary bone cyst, aneurysmal bone cyst, intraosseous ganglion cyst, and epidermoid cyst. For each type, it covers locations, pathogenesis, histology, imaging appearance, and treatment options. It also briefly mentions several conditions that can resemble cystic bone lesions. The document provides detailed information on solitary bone cysts and aneurysmal bone cysts.

1. Cystic bone lesions
DR.ABHINAV KESARKAR

2. Cyst ???
• Cysts are closed capsule or sac-like structures,
typically filled with liquid, semisolid or
gaseous material - very much like a blister.
• A cyst is not a normal part of the tissue where
it is located. It has a distinct membrane and
division on nearby tissue - the outer or
capsular portion of a cyst is called the cyst
wall. If the sac is filled with pus it is not a cyst,
it is an abscess

3. Cystic lesions of the bone.
1. Solitary bone cyst (unicameral bone cyst)
2. Aneurysmal bone cyst
3. Intraosseous ganglion cyst
4. Epidermoid cyst

4. conditions resembling cystic bone
pathology
1. Fibrous dysplasia
2. Chondromyxoid fibroma
3. Chondroblastoma
4. Giant cell tumour
5. Fibrous cortical defect
6. Brown tumor
7. Hydatid cyst (rare)

5. Unicameral bone cyst
• This is the lesion of the rowing bone annd considered to be
more a developmental or a reactive lesion.
• Age : first 2 decades of life
• sex preponderence : M > F [2:1]
• Location : proximal humerus and femur in growin bones. In
adults , ilium and calcaneum most common sites. But can
occur in any of the extremity.
• The lesion are most active in maturing bones and heal
spontaneously at maturity.

6. Types of UBC
1. Active cystic lesion - within 1cm of physis
2. Benign latent cysts – towards diaphysis

7. Pathophysiology
• Still elusive
• Focal defect in metaphyseal remodeling blocks interstitial
fluid drainage which leads to increased pressure in conduits
and thus cell necrosis and accumulation of fluid.
• Recent studies showed that Unicameral bone cyst fluid
possesses N-acetyl-beta-D-glucosaminidase, beta-
glucuronidase, PZ-peptidase, cathepsin D, acid
phosphatase, N-acetyl-beta-D galactosaminidase, and beta-
galactosidase activities. The activities of lysosomal enzymes
in the cyst fluid are, as a rule, higher than in the serum,
whereas the total protein content is lower

8. • The presence in the cyst cavity of extracellular
lysosomal enzymes and collagen degradation
products testifies to the permanent corrosion of
the cyst cavity walls from the inside as well as to
the increase in the osmotic pressure of the cyst
fluid. Lysosome destruction should be regarded
as an important pathogenetic factor that requires
surgical or pharmacologic correction or both in
the course of bone cyst management.
The role of lysosomes in the pathogenesis of unicameral bone cysts
(central institute of traumatology and orthopedics ,USSR)

9. Unicameral bone cyst is filled with straw colored fluid rich in prostaglandins,
GAGs, mucopolysaccharides and lysosomal enzymes. This fluid contributes to
bone resorption.

10. UBC HISTOLOGY
LINED BY FIBROUS
MEMBRANE < 1MM THICK
COMPOSED OF
FIBROBLAST,IMMATURE
BONE,MESENCHYMAL
CELLS AND LYMPHOCYTES

11. RADIOLOGY
• lytic, centrally located , purely lytic lesion
•No periosteal reaction
•Fallen leaf sign
•Prominent osseous ridges give it a
multiloculated appearance

12. UBC IN CALCANEUM

13. MRI
Fluid level seen on MRI.

14. TREATMENT
• Small asymptomatic lesion in upper limbs –
wait n watch with serial x rays
• Larger lesions , especially located at stress
points prone to pathological fractures –
CURETTAGE (with or without bone graft and
internal fixation)
• Pathological fractures in upper limb can be
managed conservatively as they can promote
healing.

15. • Intra lesional methyl prednisolone (80 – 200
mg) has shown good results.
• Exact MOA not known but is hypothesised to
be due to antiprostaglandin effect and
reduction of intracavitory pressure.
• If no radiographic signs of healing , repeat
doses at 2 months.

16. Other materials used for percutaneous
treatment of UBC
1. Autogenous bone matrix mixed with allograft
2. High porosity hydroxypatite
3. Calcium sulfate [STIMULAN]
4. Calcium phosphate bone substitute
5. Prp ( ?)

17. UBCs resistant to percutaneous
treatment
• Multiloculated
• Large size
• Age less than 10 years
• Radiographically active lesion

18. Aneurysmal bone cyst
• Locally destructive blood filled reactive lesions
of bone .
• Site – proximal humerus , distal femur ,
proximal tibia and spine.
• Usually occurs in second decade of life and
with slight female preponderance.

19. pathogenesis
• Uncertain
• Postulated to occur due to local circulatory
disturbance leading to increased venous pressure
and production of local haemorrhage
• based on angiographic, immunohistochemical
and electron microscopic studies, dilated and
tortous efferent veins became visible in the late
venous phase. Due to the impedance of venous
flow, the intracystic pressure increases and the
small veins become dilated causing formation of
aneurysmal slits.

20. MICROSCOPY
HAEMORRHAGIC TISSUE WITH
CAVERNOUS SPACE SEPARATED
BY STROMA . CAVITY LINED BY
COMPRESSED FIBROBLASTS
AND HISTIOCYTES.

21. Patient usually complaints of mild to
moderate pain intermittently which
becomes continuous over a period of
time.

22. Expansile lytic lesion,
elevating the periosteum but
confined within the shell of
cortex, and is eccentrically
located in metaphyseal
region.

23. CT - ABC

24. 3D RECONSTRUCTION VIEW OF
FIBULAR HEAD ABC

25. TREATMENT
• SURGICAL INTERVENTION IS MAINSTAY AND INCLUDES
1. EXTENDED CURETTAGE AND GRAFTING
2. MARGINAL RESECTION
3. PREOPERATIVE EMBOLISATION IN LESONS OF SPINE AND
PELVIS TO REDUCE RISK OF BLEEDING.
4. LOW DOSE RADIATION

26. • RECURRENCE RATE AFTER CURETTAGE IS 10 -20 %
• RECURRENCE HAVE BEEN CO RELATED WITH
Age less than 15 yrs
centrally located cysts
incomplete resection

27. Intraosseous ganglion cyst
They are intra osseous extension of ganglion
of soft tissues.

28. Intraosseous ganglion is a benign,
nonneoplastic bone lesion with
histological similarity to that in soft
tissue . Intraosseous ganglion contains
mucoid viscous material with no
epithelial or synovial lining . Peak
incidence of intraosseous ganglion is in
the 4th and 5th decades of life, and it is
rare in children

29. Treatment
• Symptomatic lesion treated by local excision
of overlying soft tissue and curettage.

30. Epidermoid bone cyst
• These are rare bone cysts filled with
keratinous material and lined by squamous
epithelium.
• Usually occur in skull and phalanges.
• They appear as rarefied defects surrounded by
sclerotic bones.
• They are considered to be traumatic origin.

32. pathogenesis
• Not known
• Theory 1 – metaplasia of cells
• Theory 2 – implantation of ectodermal cells in
periosteum due to trauma. Still a topic of
debate.

33. treatment
• Excision for smooth walled cells.
• Friedlanders and sontag suggested
amputation of the affected part more wise.

34. THANK YOU