Cryosurgery Flashcards
What are the cryogenic agents?
Liquid nitrogen, NO, CO2
What temperature does benign tissue destruction occur at? Malignant tissue?
- Tissue destruction occurs between -10 and -20C
2. Malignant cells are completely destroyed between -40 and -50 C
What are the portable canisters used for?
Portable canisters are only for benign lesions (propane, dimethyl ether)
What is the physiology of cryosurgery?
Freezing of epidermis results in separation of epidermal layer from basal membrane
What are the immediate responses of cryosurgery?
- Erythema
2. Hyperemia
What are the responses to cryosurgery within 24-48 hours?
- Edema
2. Blister formation
What are the responses to cryosurgery within 72 hours?
- Treated lesion becomes bloodless
- Crust begins to form
- Crust then gradually withers away over next several days
- Re-epithelialization occurs from outer margin inward
What are the benign indications for cryosurgery?
- Verrucae/ Condyloma acuminatum
- Seborrhea keratosis
- Lentigo
4, Molluscum contagiosum - Dermatofibroma
- Hypertropic scars
- Acrochordon
What are the precancerous and cancerous indications for cryosurgery?
- Actinic keratosis
- Malignant: only by specialist
A. BCC
B. SCC in situ
C. Lentigo maligna
If dx is not clear, a biopsy should be performed
What are the absolute contraindications to cryosurgery?
- Sensitivity or adverse reaction to cryosurgery
- Any undiagnosed lesion in which malignancy is suspected- Refer
- Melanoma
- Nonacceptance of possibility of skin pigment changes
- Areas of compromised circulation
- Recurrent or Sclerosing BCC
What are the relative contraindications to cryosurgery?
- Dark complexion
- An extremity w/ vascular compromise
- Cryoglobulinemia
- Autoimmune disorder
- Raynaud’s disease
- Areas around hair, ie eyebrows
- Body area w/ superficial nerves (ie angle of jaw, lateral aspects of digits, ulnar fossa of elbow)
What equipment is needed for cryotherapy?
- Various delivery devices
- Assorted cryo-probe tips
- K-Y jelly
What are the possible delivery devices for cryosurgery?
- Brymill Cryogun (liquid nitrogen)
- Verruca Freeze (
- Histofreezer
What is the method of application for brymill cryogun?
- Contact probes or spray-tipped nozzles can be used
2. Perpendicular spray most effective
How is the pt prepped for cryosurgery/
- Informed consent
- Discuss Pros/Cons
- Inform pt that they will feel discomfort/pain which may last up to 20-30 mins
- Pt supine for safer treatment environment
- Topical anesthestics may be used as cream or gel prior to tx
- Inform pt that it is common for blistering to occur
What is the method of application for verruca freeze?
- Hold spray tip 1-2 cm from lesion surface and gently squeeze trigger mechanism
- Apply spray in a pulsatile rotary spiral rather than continuous
- May use disposable ear cone to confine spray
What are the general guidelines regarding the halo for effective destruction of the lesion?
In general, a halo of 1 mm around the base of lesion should be produced to cause effective destruction of many benign lesions
What is the recommended halo size for Verrucae/actinic keratosis/acroch?
1-2mm
What is the recommended halo size for Molluscum contagiosum/seborrheic keratosis?
1 mm
What is the recommended halo size for Lentigo/dermatofibroma/sebaceous hyperplasia?
0-1 mm
What is the depth of the freeze?
The depth of the freeze is estimated to be approx 1.5 times the lateral spread of the freeze (the halo)
How should a raised lesion be treated?
For a lesion that is raised, the lesion should be treated w/ continuous freeze, called an ice ball, that encompasses the lesion (start at distal most part of lesion)
What is the most effective destruction technique?
Freeze rapidly, thaw, re-freeze
What is recommended freeze time for Plantar warts/skin tags/seb keratoses (after debridement)?
40 sec
What is recommended freeze time for molluscum contagiosum?
20 sec
What is recommended freeze time for actinic keratosis (facial)?
15 sec
What is recommended freeze time for actinic keratosis (non-facial)?
40 sec
What are the danger sites for cryosurgery?
- eyes
- ears
- side of mouth
What are the potential complications of cryosurgery?
- Pigment cells/hair cells may be destroyed
- Area poor circulation susceptible to prolonged ulcer formation
- Tissue pathology documentation is not possible
- Peripheral neuropathy can result when areas adjacent to nerves are frozen
- Overtreating a lesion may result in unnecessarily destroying healthy tissue and creating scars and hypopigmentation
- Undertreated lesions can always be re-treated at a later date if needed
What pt education needs to be provided for cryosurgery?
- Edema/erythema are to be expected and pain may be uncomfortable enough for modifying activities
A. With plantar warts, may need to refrain from running or walking - Tell patient to watch for signs of infection and contact if fever, chills, increased pain or redness or if blister is more severe than the patient can tolerate
- Inform pt that it is possible to have redness at site for several days or even weeks (which may not necessarily mean it is infected)
