Fundamentals of Cryosurgery, Biopsy, and Dermoscopy

Idaho Academy of Family Physicians May 13, 2016

Steven Mings, MD Gem State Dermatology Clinical Assistant Professor University of Washington

Objectives

 Know indications and techniques for using cryotherapy to treat common dermatologic conditions  Know indications and techniques for biopsies to treat common dermatologic conditions  Gain understanding of fundamentals of dermoscopy

Cryosurgery

 Purpose: For rapid treatment of common skin conditions  Benign lesions: warts, seborrheic keratoses  Premalignant lesions: actinic keratoses  Malignant tumors: Basal cell/squamous cell carcinomas  MUST KNOW THE DIAGNOSIS

1 Cryosurgery

 Tissue destruction: -10 to -20 C.  Malignant cell kill: -40 to -50 C.

 Chemical refrigerants -40 to -94 C.  Cold cryoprobes -90 C.  Liquid Nitrogen -196 C.

Chemical Refrigerants

 Verruca-Freeze  Low start-up costs  Useful for satellite offices  Not approved treatment for malignant lesions

Verruca Freeze

 Speculum size (2-12 mm) that encompasses lesion  1 “freeze” cycle = » Fill speculum with spray 1/8- 1/4 inch (3-6 seconds) » Allow fluid to evaporate (20-25 sec.)  130 “freezes” per cannister  $200 start-up costs  Long shelf life- 4-5 years

2 Cryoprobes

 Nitrous oxide cryoguns  Tanks with cart, hand gun, pressure gauge and regulator  Useful if liquid nitrogen not available

Nitrous Oxide

 Put water soluble gel to lesion  Select probe size  Apply activated cryogun probe tip to skin

3 Liquid Nitrogen

 Most common form of cryotherapy  Widely used by dermatologists  Most effective with coldest temperature of all options  Cheap after set-up costs  Easy to learn, quick to apply  Multiple lesions at one time

Liquid Nitrogen

Advantages for patient  No local anesthetic needed  Pain tolerable  No sutures  Wound care relatively easy  Coldest freezing temperature

Liquid Nitrogen

Disadvantages for clinician  Start-up costs $1000  Storage facilities  Filling canisters

4 Liquid Nitrogen

 Boiling point -196 C.  Cellular destruction: » ice crystal formation » cellular dehydration » protein and enzymatic denaturization  Destruction more pronounced with: » rapid freeze » slow thaw cycle

Liquid Nitrogen: Equipment

 Storage tank= Dewars  2-30 L, filled q 3-4 weeks  Costs: Tanks: Holding time Costs » 5 L 4-5 weeks $639 » 10 L 6-8 weeks $700 » 20 L 8-12 weeks $1100 » 30 L 14-16 weeks $1000

Liquid Nitrogen: Equipment

 Filling Dewars; pouring, ladles or devices  Devices affixed to dewar: Ladels $50-100 Valve: $550 Tube: $400

5 Liquid Nitrogen: Equipment

Thermos bottle with hole and cotton tipped swab or Cry-AC Spray/cryogun (C-tip, mini-gun)

10 oz 16 oz 12 oz $670 $670 $650 12 hr 24 hr 24 hr

Cryosurgery

 Cotton tipped swabs

Cryosurgery

 Use of pickups to apply improves precision and decreases risk of PIH in pedunculated lesions  Specially designed forceps hold temperature for 2-3 minutes: cost $250  Can use regular metal forceps as well.

6 Cryosurgery

 Frozen areas turn white = “freezeball” or “iceball”  Depth and width are important » Pulse technique can increase depth – Without increasing width  Lethal Zone » Tissue temp < -20 C. » 1-3 mm inward from outer margin iceball  Freeze 1-3 mm beyond lesion edge

Dermatologist “enjoying” the sun on the beach

Cryosurgery Video

7 21 Days Later

Cryosurgery

Remember …..  Always best to underfreeze rather than overfreeze  Hold canister perpendicular to skin  Many advocate multiple freeze/thaw cycles, but other than in plantar warts I couldn’t find that supported in literature

Risks

 No pathology with procedure » Most significant of all risks  Incomplete response » Ring wart recurrence  Significant pain “cry” o surgery  Rare persistent numbness

8 Risks (continued)

 Post inflammatory pigment change » Hypo or hyperpigmentation » More common with vigorous freeze and darker skin, on legs  Blister formation  Infection  Verbal or oral consent prior to procedure is recommended

Cryosurgery: Freezeball Time

 Freckles/lentigos: 3-5 seconds  Small papules: 5-10 seconds  Seborrheic Keratoses: 10-40 seconds  Actinic keratoses: 10-40 seconds  Required freeze duration depends on thickness of lesion  Think three dimensionally

Cryosurgery: Freezeball Size

 1mm- freckles/lentigos  1-2 mm- most benign skin lesions  2-3 mm- most warts » Viral DNA can be found as far as 1 cm from visible lesion  2-3 mm- most actinic keratoses

9 Resistant Wart

Cryosurgery: Effectiveness

Low  Vascular lesions: e.g. angiomas  Keloids  Basal cells and squamous cells

Cryosurgery: Superficial BCCa/SCCa

 Establish pathological diagnosis first  Success rates reported as high as 95% but require vigorous freezes, using temperature probes.  Generally I do not use cryo for these lesions and do not recommend except in special circumstances.

10 Cryosurgery

 Thermocouple

 $500-700 for temperature monitor and thermocouple needle

Cryosurgery: Effectiveness

Medium

 Dermatofibroma  Molluscum  Prurigo nodularis  Sebaceous hyperplasia

Cryosurgery: Effectiveness

Medium-High  Seborrheic keratosis  Verruca * » Occasionally, treating some verruca or molluscum can provoke immune destruction of multiple lesions  Condyloma acuminata  Freckles (ephilides)

11 Cryosurgery

 Verruca: » Often resistant to any therapy – 50/50 with cryotherapy, shave excision, and with home OTC tx » Warts on hands (periungal most resistant) » Less efficacy with multiple lesions » Occasionally, treating some verruca or molluscum can provoke immune destruction of multiple lesions

12 Cryosurgery: Effectiveness

High  Actinic keratosis  Seborrheic keratosis  Lentigos

Cryosurgery: Special Populations

 Children » In general avoid b/c pain » Use EMLA cream if needed  Useful modality for those on anticoagulants, those with pacemakers and those allergic to anesthetics

Cryosurgery

DO NOT FREEZE  If you do not know diagnosis  Skin cancers in general  Melanoma or any possibility  Compromised circulation  Cosmetically sensitive areas on dark skinned patients  When multiple prior freezes unsuccessful

13 Conclusions

 Cryosurgery is safe, convenient, effective and can be done quickly  Know the diagnosis first, and understand the risks  Perform patient education before the procedure  Beware of the lack of histological diagnosis!

14