Questions and Answers
What is the primary function of cryosurgery?
Which cryogen is considered the cryogen of choice for dermatological cryosurgery?
What effect does extracellular ice formation have on cell membranes?
What is a mechanism of direct tissue injury in cryosurgery?
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What is an effect of osmolarity changes during cryosurgery?
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What is the result of rapid freezing and slow thawing in cryosurgery?
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Which of the following is NOT an indication for cryosurgery?
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What is a critical factor influencing the effectiveness of cryosurgery?
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Which condition is considered a malignant lesion suited for cryosurgery?
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Which of the following is an absolute contraindication for cryosurgery?
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Study Notes
Cryotherapy Overview
- Cryosurgery involves localized freezing to destruct or remove living tissues safely and effectively.
- It is cost-effective, reproducible, repeatable, and a straightforward office procedure with excellent healing and cosmetic outcomes.
Cryogens
- Liquid nitrogen is the preferred cryogen for dermatological applications, especially for malignant skin lesions.
- Other cryogens and their freezing points:
- Liquid nitrogen: -196°C
- Liquid oxygen: -183°C
- Nitrous oxide: -89°C
- Solidified CO2: -78°C
- Dimethyl ether: -24°C
Mechanisms of Tissue Injury
- Direct Tissue Injury: Involves heat transfer, inflammation, and direct cellular damage.
- Indirect Tissue Injury: Results from vascular stasis and subsequent tissue hypoxia.
- Ice Formation and Cellular Injury: Rapid heat transfer during cryogen application leads to ice formation, damaging cell membranes and organelles.
- Osmolarity Changes: Increased solute concentration from extracellular ice formation disrupts cell membranes.
- Thermal Shock & Denaturation: Rapid freezing followed by slow thawing enhances tissue destruction.
- Vascular Changes: Ischemic necrosis occurs due to microthrombi, leading to tissue destruction.
- Cryoimmunomodulation: Low temperatures may enhance immune response against viral/tumor cells.
Indications for Cryosurgery
- Viral Lesions: Warts, molluscum contagiosum, condyloma acuminata.
- Benign Lesions: Cystic acne, acne scars, keloids, skin tags, seborrheic keratosis, and others.
- Premalignant Lesions: Actinic keratoses, leukoplakia, Bowen's disease.
- Malignant Lesions: Basal cell carcinoma, squamous cell carcinoma, lentigo maligna melanoma.
- Not suitable for large tumors (>2 cm), recurrent lesions, or anatomical locations like feet or lower legs.
Contraindications
- Absolute Contraindications: Blood dyscrasias, cold urticaria, areas with compromised circulation, significant sensitivity to cryotherapy.
- Relative Contraindications: Keloidal tendencies, autoimmune diseases, ongoing immunosuppressive treatment, and more.
Pre-procedure Steps
- Obtain informed consent after explaining the procedure.
- Document pre-treatment photographs, if necessary.
- Perform a biopsy for malignant/premalignant conditions.
- Administer analgesics and clean the treatment area with antiseptics.
Cryosurgical Techniques
- Dipstick Technique: Simple but less effective; cotton tip applicator in liquid nitrogen applied to lesion.
- Spray Technique: Most popular; liquid nitrogen sprayed on lesions using varying methods for desired coverage.
- Cone Spray Technique: Concentrates cryogen to minimize lateral spread; higher tissue destruction rate.
- Intralesional Cryotherapy: Delivers cryogen through a needle directly into deeper scars or lesions, preserving the epidermis.
- Forceps/Clamp Technique: For small skin tags, using a hemostat dipped in liquid nitrogen.
Procedure Details
- Effective freeze times vary by condition; for example:
- Common warts: 10-15 seconds
- Keloids: 20-30 seconds
- For tumors, at least two freeze-thaw cycles of 30 seconds with a 5-minute thaw period are required.
Post-procedure Observations
- Initially, a white ice field forms, followed by a violet halo and hemorrhagic blister which eventually forms an eschar.
- Frozen area contracts within 10-14 days; follow-up is needed to assess healing and manage potential complications.
Complications
- Immediate Complications: Edema, blister formation, pain, bleeding, and vasovagal responses.
- Delayed Complications: Hemorrhagic blisters, wound infections, delayed healing, and rare hypertrophic scarring.
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Description
This quiz covers the basics of cryotherapy, focusing on the overview of cryosurgery and the various cryogens used. It also delves into the mechanisms of tissue injury, including direct and indirect effects on cellular structures. Test your knowledge of this effective dermatological procedure and its applications.
