This document provides information on the management of hydatid cyst and osteoid osteoma. It discusses the classification, diagnosis, and treatment options for hepatic hydatid cysts, including PAIR (Puncture, Aspiration, Injection, Re-aspiration) technique. It also covers the presentation, diagnosis, and treatment of osteoid osteoma, noting that radiofrequency ablation is currently the treatment of choice due to its safety, effectiveness, and minimal invasiveness compared to other options such as surgery. The document provides detailed steps for performing radiofrequency ablation and managing the risks.

1. MANAGEMENT OF HYDATID
CYST AND OSTEOID OSTEOMA
PRESENTER-DR.SANGEETA JHA
MODERATOR-DR.ABHAY KUMAR

2. HYDATID DISEASE
• zoonotic infection caused by larval forms of Echinococcus granulosus.
• Cystic hydatid disease usually affects the liver (50–70%) and less frequently the
lung, spleen, kidney, bone, and brain.
Hepatic echinococcal cyst-
 remain asymptomatic until their expanding size or their space occupying effect
result in symptoms
 abdominal pain or a palpable mass in the right upper quadrant-most common
presesntation.
 Rupture of or episodic leakage from fever, pruritis, urticaria, eosinophilia, or
anaphylaxis.
 Infection of the cyst -liver abscesses
 mechanical local complications -mass effect on bile ducts and vessels that can
induce cholestasis, portal hypertension and Budd-Chiari syndrome.
 the presence of daughter cysts in an older cyst represents a significant risk of
recurrence after surgery

3. CLASSIFICATION-for liver hydatid cysts
based on their ultrasound appearance
1.Gharbi classification
2.WHO Informal Working Group on Echinococcosis (IWGE) classification
Hassen Gharbi classified hepatic hydatid into five types based on
sonographic appearance.
WHO classification is almost the same as Gharbi’s, with Gharbi type II
corresponding to CE 3A of the WHO classification
predominantly solid cyst with daughter cysts, which was not included
in Gharbi’s classification is in class 3B of WHO classification.

7. Unilocular, cystic lesion(CL) with uniform anechoic
content with no definite cyst wall.
If they are CE ---
 Active
 caused by CE at an early stage of development
 usually these cysts are not fertile.
 Ultrasound does not very diagnostic.
 Differential diagnosis of these cystic lesions
requires further diagnostic techniques.

8. • Unilocular, simple cyst with uniform
anechoic content.
exhibit fine echoes due to shifting of brood
capsules which is called hydatid sand
(“snow flake sign”).
• Cyst wall is visible.
• Status: active.
• Usually fertile.
USG-is diagnostic
• Pathognomonic signs include visible cyst
wall and snow flake sign.

9.  Multiseptated cysts; which produce “wheel-like”
structures
 presence of daughter cysts is indicated by “rosette-
like” or “honeycomb-like” structures.
 Cyst wall normally visible.
 Status: active.
 Usually fertile.
 Ultrasound features are pathognomonic.

10.  Anechoic content with detachment of laminated
membrane from the cyst wall visible as floating
membrane or as “water-lily sign”
 Cyst is less rounded because of decrease of intra-
cystic fluid
Pressure.
 Status: transitional [Cyst which may degenerate
further or may give rise to daughter cysts.]
 Ultrasound features are pathognomonic.

11.  Heterogenous hypoechoic or hyperechoic
degenerative contents
 No daughter cysts.
 May show a “ball of wool” sign which is
indicative of degenerating membranes.
 Status: inactive.
 not fertile.
 US features are not pathognomonic and
further diagnostic tests are required to
ascertain a diagnosis

12.  Cysts characterized by thick calcified wall
that is arch shaped, producing a cone
shaped shadow. Degree of calcification
varies from partial to complete.
 Status: inactive.
 not fertile
 Diagnosis is uncertain. Features are not
pathognomonic but highly suspicious .

13. PAIR
• PAIR (Puncture, Aspiration, Injection, Re-aspiration)
• Developed in the middle of 1980s for the treatment of intra-abdominal
Cystic Echinococcosis (CE).
• However, reports exist about the use of this treatment for cysts in the lung
and extra-abdominal or extra-thoracic localizations.
• The drainage is performed with a fine needle or a catheter, followed by
the killing of the protoscolices remaining in the cyst cavity by a
protoscolicide agent.

14. • If a catheter is temporarily left in the cyst after the procedure for drainage
(D), the acronymPAIRD should be preferred.
• If numerous and large daughter cysts are present, an alternative
percutaneous technique“Percutaneous Puncture with Drainage and
Curettage” (PPDC) may be used.
• PAIR is performed under ultrasound (US) or Computer Assisted Tomography
(CT) guidance.
• Feasible in in types CE1, CE2 and rarely CE3 of the WHO classification of
Cystic Echinoccosis cysts.
In CE3,CE4 and CE5 surgery is preffered

15. INDICATIONS FOR PAIR
Patients with:
• Anechoic lesion ≥ 5 cm in diameter (CE1)
• Cysts with daughter cysts (CE2), and/or with detachment of membranes (CE3)
• Multiple cysts if accessible to puncture
• Infected cysts
Can Also be done in
• Pregnant women
• Children >3 years old
• Patients who fail to respond to chemotherapy alone
• Patients in whom surgery is contraindicated
• Patient who refuse surgery
• Patients who relapse after surgery.

17. CONTRAINDICATIONS FOR PAIR
• Non-cooperative patients
• inaccessible or risky location of the cyst in the liver
• Cyst in spine, brain and/or heart
• Inactive or calcified lesion
• Cysts communicating with the biliary tree
• Cysts open into the abdominal cavity, bronchi and urinary tract

18. HOW TO PERFORM PAIR
Basic Requirements
Only personnel trained in interventional ultrasound should perform this procedure,
supported by a person trained in resuscitation procedures
Equipment, Supplies, Drugs (minimum requirements) :
• Ultrasound equipment (portable apparatus) with a 3.5 - 5 MHz probe
• Needles (lumbar puncture needles, “fine needles”, especially for multiple daughter
cysts)
• Drainage Catheters for large cysts (> 5 cm)
• 95 % alcohol or hypertonic (at least 15 %) saline as protoscolicide agent
• “Fast test kit” for checking the presence of bilirubin in the cystic fluid and thus rule
out possible connections with biliary tree
• Drugs to be used in case of allergic reactions-anaphylaxis (epinephrine,
hydrocortisone); and basic resuscitation equipment
• Blood pressure measurement and intravenous catheter must be left in the forearm
during the procedure, so that resuscitation can take place immediately, if needed.

19. Additional Equipment, Supplies, Drugs for optimal situation
• CT, ERCP (Endoscopic Retrograde Cholangiopancreaticography), fluoroscopy
• Contrast medium to be injected in the cystic cavity to exclude possible
connections with the biliary tree after the first aspiration of fluid
• Radiologic equipment for cystography using contrast medium
• Parasite examination kit
• Serologic/Antigen detection kit (ELISA, IHA)
• Biochemistry equipment for measurement of glucose and electrolytes in the
fluid

20. PROCEDURE:
If patient is on b-blocker: stop the treatment at least one week before
the procedure or replace it by another drug.
Treatment with albendazole at least 4 hours before procedure (one
week for some teams) and during the following 1st month.
Puncture under US guidance with LP needle
Then aspirate atleast 10-15 cc of cystic fluid and the examine fluid -
1. If protoscolices are absent and/or antigen detection negative: stop
procedure(probably non-parasitic cyst)
b. If protoscolices are present and biochemical fluid data are positive
continue PAIR procedure

21. Then inject contrast medium into the cyst and do cystography under
fluoroscopy
a. If there is communication with bile ducts: stop the procedure;
contrast medium may be left in the cyst as a substitute of
protoscolicide
b. If no communication with bile ducts: proceed further
Replace the LP needle with catheter
Aspirate cytic fluid and inject 95% ethanol solution or hypertonic
saline (1/3 of the amount of aspirated fluid)
Patient should be left in right lateral,left lateral, prone and supine
positions for 5 minutes in each position.
Then reaspirate the alcohol solution
If needed drainage tube should be left for some days until the output
is less than 10 ml/day.

24. The steps of the puncture procedure
The critical point is the angle of puncture: normal liver parenchyma must be
present between the puncture point and the surface of the cyst to avoid leakage
of cyst fluid.
Direct puncture of a cyst close to the abdominal wall must be avoided.

25. The steps of the puncture procedure (CT images) in three patients with CE1 cysts: see the angle of puncture
(figures1, 2 and 3), the aspiration of cyst fluid (figure 4), the appearance of the cyst after injection of contrast
medium (figures 5, 6 and 7), and after reaspiration of the protoscolicide agent

26. Patients’ follow-up: comparison of CT images before and 6 months after PAIR

27. RISKS OF PAIR PROCEDURE
• Same risks as any puncture ( haemorrhage, mechanical lesions of
other tissues, infections )
• Anaphylactic shock or other allergic reactions
• Secondary echinococcosis caused by spillage
• Chemical ( sclerosing ) cholangitis if cysts communicate with the
biliary tree
• Sudden intracystic decompression, thus leading to biliary fistulas
• Persistence of satellite daughter cysts
• Systemic toxicity of alcohol or hypertonic saline in case of large cysts
[total volume injected must be carefully calculated]

28. BENEFITS OF PAIR
• Minimal invasiveness
• Reduced risk compared with surgery
• Confirmation of diagnosis
• Removal of large numbers of protoscolices with the aspirated cyst fluid
• Improved efficacy of chemotherapy given before and after puncture
(probably because of an increased penetration of antihelminthic drugs into
cysts re-filling with hydatid fluid )
• Reduced hospitalization time
• Cost of the puncture and chemotherapy usually less than that of surgery or
chemotherapy alone.

29. RISKS OF CHEMOTHERAPY
• Potential risk of embryotoxicity and teratogenicity (observed in early stage
of pregnancy in some laboratory animals,so PAIR should without
chemotherapy during early pregnancy)
• Hepatotoxicity (transient increase of aminotransferases), neutropenia,
thrombocytopenia, alopecia

33. OSTEOID OSTEOMA
TREATMENT OPTIONS
May be self limited[probable theory is tumour infarction]
Medical management-aspirin or other NSAIDS.
Surgical management- En block open resection
CT guided percutaneous resection
Radiofrequency ablation-most effective

34. Disadvantages of medical management
 Gastrointestinal complications.
 Articular or periarticular osteoid osteomas are resistant to conservative therapy.
Disadvantages of surgical management{en block resection}
 Causes bone defect -vulnerable to fracture
 Incomplete Resection –require a second surgery
 Difficult location-surgery may be CI or increases the risk of injury to adjacent
structures
 The excision of articular and epiphyseal lesions may require arthrotomy, with
causes impairment of bone growth, joint mobility, or both.
Other postsurgical complications include
 hematoma and infection.
 Long hospital stay
 Weight-bearing activity is limited for 1–6 months after surgery.
 use of crutches may be necessary in cases involving the lower limb.

35. CT-guided percutaneous resection-
Less invasive alternative method of treatment
Reduced hospital stay
Earlier resumption of weight-bearing activity.
However, it is associated with postoperative complications similar
to those of open surgical excision
including hematoma, osteomyelitis, and fracture. The failure rate
with this method of treatment in one patient series was 16% .

36. RADIOFREQUENCY F ABLATION
current method of choice for treatment
The procedure is safe and effective
widely available,
short duration procedure-The average procedure can be
performed in approximately 90 minutes, and the
duration of post procedural hospitalization for observation is 3–24
hours
All daily activities may be resumed immediately without the use
of a cast, splint, or other external supportive apparatus

37. Relative contraindications to RF ablation
• Lesion in the hand or the spine (<1 cm from vital structures such as
nerves)
• Pregnancy
• Cellulitis
• Sepsis
• Coagulopathy
Lesions with a nidus larger than 1 cm generally require multiple
applications of the electrode in various positions

38. RF ablation:
Performed under CT guidance
under general, spinal,or propofol-induced anesthesia.
{Local anesthesia alone usually results in insufficient pain
control,particularly during entry into the nidus of the lesion}
All patients should undergo preprocedural screening, during which
a medical history is obtained and a physical examination and basic
laboratory analyses are performed.
The skin overlying the lesion must be intact at physical
examination.
Development of any changes such as rash or infection in the skin
overlying the planned entry site will result in postponement or
cancellation of the procedure.

39. RFA
STEP BY STEP
1. LESION LOCALIZATION
Performed by acquiring multiple thin-section CT images at the level of the
osteoid osteoma, within a region of interest of approximately 4 cm
 Multiplanar reformatted images may be helpful for preprocedural planning
A single skin entry point is planned for lesions less than 1 cm in diameter.
For lesions larger than 1 cm, multiple skin entry points are required to
obtain the 1-cm-wide ablated margin required for treatment success

40. Lesion localization in a 17-year-old
boy. Axial thin-section CT image obtained with
the leg in external rotation to facilitate needle
placement clearly depicts an osteoid osteoma with a
radiolucent nidus (arrow) in the femoral neck.
Coronal reformatted CT image
shows a corticaly based sclerotic lesion (arrow),
a finding consistent with a diagnosis of osteoid
Osteoma.

41. 2.APPROACH PLANNING
Radiopaque markers are placed on the skin overlying the lesion.
The preferred approach is at an angle perpendicular to the cortical surface of
the involved bone.
The route is planned so as to avoid any adjacent neurovascular structures
In some cases, entry through the opposite normal cortex may be necessary to
avoid overlying critical structures.

42. Approach planning. Axial CT image of the proximal femur demonstrates the preferred angle of approach,
nearly perpendicular to the cortical surface (arrow). This approach was planned to avoid an adjacent
neurovascular bundle (arrowhead)

43. 3.TIME-OUT AND GROUNDING PAD
After the entry site is marked, a time-out should be taken to
confirm the patient’s identity and verify the side and site of the
planned procedure.
Grounding pads are then put in place to inhibit the transmission of
current through the patient
The targeted extremity should be secured to prevent movement
during biopsy and ablation.
The skin overlying the lesion is then prepared and draped in
accordance with sterile technique.
 One gram of cefazolin sodium is administered intravenously
before the start of the procedure

44. Placement of grounding pads. Grounding
pads placed on the ipsilateral thigh and
contralateral extremity help minimize the
transmission of RF energy through the
body and help prevent excessive heating.

45. 4.SKIN ENTRY
A bone biopsy system is used to obtain percutaneous access to the lesion,
perform a biopsy, and guide the RF electrode for ablation..
Typical components include a penetration cannula and inner stylet, a coaxial
drill tip to penetrate the outer cortex, and a coaxial biopsy needle.
 Local anesthesia of 1% lidocaine solution via a superficial skin along a
preselected path to the bone surface.
 The cannula with stylet is then inserted and advanced through the soft tissues
to the bone surface
localizing scan is performed to confirm that the cannula is correctly
positioned.
The inner stylet should be removed before scanning to avoid metallic artifact,
which may obscure a small lesion..

46. Bone biopsy system.
(a) Photograph shows a 14-gauge penetration cannula (large
green cap) with inner stylet (smaller green cap), coaxial drill tip (white cap), and
coaxial biopsy needle (blue cap). (b) Photograph provides a magnified view of the tips
of the instruments in a.

47. Skin entry and verification of cannula positioning.
Spot CT image shows appropriate positioning of the cannula for biopsy of the lesion. After
the cannula and inner stylet are advanced to the bone surface, the stylet is removed to
avoid a metallic artifact, which might obscure a small lesion at verification scanning.

48. SUPERFICIAL BONE ENTRY AND DRILLING
Once the cannula is appropriately positioned,upward traction should be
exerted on the skin and soft tissues around the cannula by using the thumb and
index finger to form a tentlike structure to prevent needle tip displacement.
 The stylet is then exchanged for the bone drill ,which is advanced through the
cannula to penetrate the outer cortex.
Spot CT images are obtained to verify the depth and direction of the bone
drill.
When the drill tip is positioned at the cortical edge of the nidus, the cannula is
advanced over the drill to maintain the position.
The drill is then retracted.

49. Bone entry.
Photograph shows the cannula containing the drill used to
penetrate the outer cortex.

50. Bone entry. Spot CT image obtained after insertion of the cannula, removal of the
stylet, and advancement of the drill through the cannula shows proper positioning of
the drill, at the cortical edge of the lesion.

51. 5.BIOPSY
Although osteoid osteoma often has characteristic clinical and imaging
findings, other neoplastic and nonneoplastic conditions may have similar
manifestations; hence, a biopsy of the lesion should be routinely
performed to help confirm the diagnosis and direct subsequent treatment.
The cannula serves as a pathway for the biopsy needle ,which is advanced
into the nidus with intermittent CT for guidance
A specimen is then removed, placed in a formalin solution, and submitted
for analysis.

52. Needle placement for biopsy.
Photographs show the cannula and needle before (a) and after (b) placement
for biopsy.

53. Spot CT images obtained at successive intervals during needle insertion (b
later than a) show the needle extending beyond the cannula and penetrating
the nidus.

54. 6. ELECTRODE PLACEMENT
The RF electrode is then inserted, with its tip directed toward the center of
the nidus , through the fixed cannula.
Spot CT images are again obtained to confirm appropriate positioning .
Prior to ablation,the cannula is partially withdrawn over the electrode to a
point more than 1 cm from the electrode tip { to prevent unintended heating
of adjacent tissue by propagation along the metal cannula }
 Spot CT images again are obtained to confirm a satisfactory position of the
electrode and cannula

55. Positioning of the electrode for ablation of osteoid osteoma.
(a) Photograph shows insertion of the electrode through the cannula and into the lesion.
(b) Spot CT image shows partial retraction of the cannula (arrow) to a position more than 1 cm proximal to the
electrode tip. This step reduces the risk of heat propagation along the metal cannula and thermal injury to soft
tissues adjacent to the lesion

56. 7.ELECTRODE CONNECTION
The grounding pad is connected to the dispersive electrode cord, which
is then plugged into the RF generator.
The RF electrode also is connected to the generator
The generator is activated with an electrical impedance value of 200–
600 Ω
RF generator settings for ablation.
Photograph shows the generator with cables
connected to the grounding pad (arrowhead) and
electrode (arrow).

57. 8.RF ABLATION
Thermal heating is applied with the RF electrode at a targeted
temperature of 90°C, with manual adjustment of output controls
during the procedure as needed to maintain a stable lesion
temperature
An automatic override temperature control helps prevent excessive
heating.
Ablation is typically performed for a total of 4–6 minutes.
Large lesions may require multiple ablation cycles with the electrode
in different positions
If necessary, the cannula may be repositioned through a separate
skin incision.
Postprocedural imaging of the lesion site is not routinely performed
because the CT features of the lesion are unchanged after ablation.

58. RF generator settings for ablation.
The numbers displayed indicate the temperature at which the automatic override is
invoked (arrowhead), planned ablation time of 6 minutes (white arrow), and 3 minutes of
ablation time remaining (black arrow). The temperature control can be manually adjusted
during ablation to ensure sufficient heating and avoid overheating.

59. PHYSIOLOGIC REACTION
A characteristic physiologic reaction like increase in the respiratory rate,
heartrate, blood pressure as well as involuntary patient motion, may
occur when the nidus of the osteoid osteoma is entered.
These changes typically abate during the procedure;
however, deep anesthesia is be needed during biopsy and ablation

60. POSTPROCEDURAL CARE
 After ablation, the electrode is removed and a local anesthetic
(bupivacaine hydrochloride) is injected via the cannula for pain relief.
 sterile dressing is applied to the skin entry site
 Pain medication may be administered as needed,
 Diet and activity are advanced as tolerated
 the patient is discharged usually within 3–4hours.
 Daily activities, except for driving, may be resumed immediately after
discharge
 Excessive stressful weight bearing and prolonged strenuous activity
should be avoided for 1–3 months following the procedure if ablation
is performed in a weight-bearing bone
 A follow-up visit is scheduled for 1 month after the procedure

61. • Clinical success of RF ablation is defined as the absence of pain 2
years after the procedure.
• Clinical success rates between 89% and 95% for primary treatment
• If residual symptoms are present, a second application of RF ablation
is safe and is often successful, with reported response rates of 80%–
90%

62. THANK YOU