Sun spots are often treated with liquid nitrogen.
Home freezing kits don’t work.
What is Cryotherapy?
Cryotherapy is freezing treatment & often used in the skin cancer clinic. The temperate of Liquid nitrogen is -195.6°C. Most of the tissue damage takes place during the thawing which is also the time when you might notice a little burning sensation. Different types of skin cell are killed at different temperatures. Melanin-producing cells are very sensitive.
The lesion freezes from the centre outwards. The skin directly under the targeted area is frozen at the deepest level. The wider the ice circle, the deeper the freeze.
What affects the amount of tissue frozen?
The most common technique of cryotherapy is spraying liquid nitrogen directly onto the lesion via a fine spray. The following factors influence the amount of skin tissue that is subjected to freezing:
- How quickly the lesion is frozen
- The duration of the freeze
- Shorter frequent bursts of spray .V. Longer less frequent sprays
- The number of cycles of cryotherapy (one is enough for solar keratosis, two or more cycles are used for actual skin cancers)
- The time between cycles
For example, a sun spot requires a single cycle freezing time of 5-15 seconds, whilst a skin cancer may require 2 cycles of 30 seconds or more.
What is Cryotherapy used for?
Cryotherapy is used to treat a huge variety of skin lesions including some types of skin cancer. The most common lesions treated are:
What are the side effects of Cryotherapy?
The procedure is normally well tolerated. However, deeper freezes required for large or malignant lesions may have significant side effects
- Discomfort or pain – for longer freeze times, or treatment of sites that are more tender (especially the ear). When pain occurs, it’s usually during the thawing stage.
- Soreness, Redness, Blister, Crusting, Swelling. Blisters are best left intact. Scabs should not be removed as they help to protect the healing wound and will fall off after a few weeks.
- Pigmentation after the procedure: usually loss of pigment but there may be increased pigment on occasion. Uncommonly, the pigmentation is permanent.
Why has my skin gone pale after Cryotherapy?
Different types of skin cancer cells are killed at different temperatures.
Melanocytes are the pigment-carrying skin cells. Unfortunately, melanocytes are killed at lower temperatures than most other types of skin cell including all the types of cell which are being targeted during cryotherapy. Therefore, pale patches are common after cryotherapy.
Shave Biopsy is the default method of skin biopsy. The biopsy is generally done ‘on the spot’ with local anaesthetic. No stitches are required.
The concept of a shave biopsy is simple. A shave biopsy razor cuts through the upper layers of skin, leaving enough skin to heal from the base. Shallow shave biopsy heals quickly with a good cosmetic outcome.
Skin cancers are graded according to their depth from the epidemis. Superficial shave biopsy is used to sample skin cancers that are located near the surface of the skin. Suspected Squamous Cell carcinoma in situ, solar keratosis, and superficial BCC may be sampled with a superficial shave biopsy. Superficial shave biops heals quickly, and aftercare is simple.
Saucerisation Shave Biopsy
Deep shave biopsy is referred to as ‘saucerisation biopsy’ because the blade is angled down, and the skin scooped out in the shape of a saucer. This type of shave excision goes well into the thickest part of the skin (the dermis). The downside of saucerisation biopsy is that the wound takes weeks to heal, and may leave a hypertrophic scar.
Saucerisation biopsy is the quickest method of sampling a suspected melanoma. To put this into perspective, a single shave done ‘on the spot’ may take 5-10 minutes (including the dressing), whilst a biopsy with stitches involves a return visit for a procedure that can take up to 45 minutes. However, Australian and International Melanoma Guidelines emphasise that biopsy with stitches (formal surgical excision) is generally the better option than shave biopsy. The problem with shaving a suspected melanoma is that the shave biopsy may leave melanoma cells behind. Inadequate depth of shave will miss the crucial ‘Breslow thickness’ that is fundamental in staging melanoma.
Despite clear guidelines, some skin cancer doctors and dermatologists favour saucerisation shave biopsy over biopsy with stitches.
Doctors achieving consistently clear margins on shaves need to be meticulous that they are not leaving melanoma cells behind. Patients with busy lives may prefer a saucerisation shave that is done ‘there and then’ at a low price. Ultimately, the patient is given the information and makes their own decision.
The concept of ‘shave excision’ is somewhat controversial. The objective of a shave excision goes beyond diagnostic sampling to providing definitive treatment of a suspected skin cancer. Deep saucerisation contrasts with ‘shave excision’ in being strictly a diagnostic procedure. Melanoma identified with a saucerisation will need formal excision.
Formal excision will usually be well-clear of skin cancer because the lesion is precisely cut along predefined margins down to the level of fat. But you can’t shave down to fat because the lesion will heal terribly. The shave biopsy blade, on the other hand, travels through the dermis which is hidden from view. The treatment is done blindly. Even ‘clear margins’ on a pathology report cannot be relied upon because the pathologists ‘bread-loaf’ the sample and are viewing only a small percentage of tissue.
Curettage is generally a better method of treating certain types of skin cancer.
What is Curettage?
A curet is a sterile surgical instrument with a sharp ending in the shape of a circle or spoon. Curettage describes the action of repeatedly scraping a lesion with a curet.
Sperficial skin cancers may be effectively treated with minimal scarring.
Curettage is normally combined with Cautery in the procedure referred to as ‘Curettage & Cautery.’
What is Curettage used for?
Curettage allows a superficial skin cancer to be removed bit by bit. Curettage is done by ‘feel’ because the skin cancer is scraped out more easily than the normally ‘tough’ underlying dermis.
Skin that has been sampled with curettage consists of lots of tiny fragments of tissue. Feel for the pathologist trying to make sense of 20 to 30 tiny fragments of skin. An initial shave followed by curettage attempts to ‘be the best of both worlds’ by combining good quality tissue sample (the shave) with treatment (Curettage).
Benign skin lesions may also be treated with curettage.
What is a Punch Biopsy?
The punch biopsy instrument is sharp, circular and hollow – the medical equivalent of an apple corer. The action of pushing the instrument down to the fat layer allows a ‘core’ of skin to pop up and be grasped gently with forceps.
Punch Biopsy is a superb method to biopsy the full depth of skin.
However, the technique is limited by the surface area that can be sampled. Punch biopsies vary in diameter from 2mm to 8mm. A 2mm may be suitable for an eyelid, whilst a 3-4mm punch or more is typically preferred for skin cancer biopsy purposes.
No stitch is necessary for a 2-3mm punch biopsy, whilst an 8mm punch biopsy will require 2 to 3 stitches. The most common size used is a 4-5mm punch biopsy which typically requires a single stitch.
Why do a Punch Biopsy?
A very small lesion may be effectively treated and sampled at the same time with a punch biopsy.
Punch biopsy is most often used as a tool to reach a diagnosis:
- of a suspected skin cancer that you literally need to get to the bottom of
- of a suspsected skin cancer where a shave biopsy may leave a cosmetically unacceptable result
- of a spreading pigmented skin cancer (lentigo maligna) on the face or neck. Multiple punches may be required
- of a rash
What are the risks of a punch biopsy?
Punch biopsy is generally considered a low-risk procedure.
Bleeding and/or infection are uncommon. Scarring is generally satisfactory.
Nerve damage is rare to very rare depending on the location of the biopsy.
What is Formal Surgical Excision?
A ‘formal excision’ indicates that the whole lesion is removed up to ‘clear margins.
Formal excision may be performed for one of three reasons:
- Initial Diagnostic biopsy. An initial ‘formal diagnostic biopsy’ has the dual function of fully removing a lesion whilst at the same time presenting the whole lesion for pathological analysis. Surgical Excision with 2mm margins is generally the biopsy of choice for a pigmented skin lesion because melanoma must be fully excised for appropriate staging.
- Diagnosis combined with treatment. Nodular BCC, for example, may be readily diagnosed with dermoscopy. A confident diagnosis allows the doctor to diagnose and treat at the same time – avoiding the need for a shave biopsy followed by formal excision at a later date.
- Excision of a lesion that has already been biopsied. Melanoma almost always requires a second procedure to remove the scar with wider margins (‘excision of scar’).
A standard formal surgical excision is in the shape of a diamond or ellipse. The procedure is sterile procedure & performed under local anaesthetic.
Flaps and grafts require a higher level of surgical training and are carried out by some skin cancer doctors, some Dermatologists, and of course plastic surgeons.
What is the length of the scar?
The rule of thumb is that the scar is 3 to 4 times the ‘diameter of the defect.’
The defect = The lesion with clear margins. Margins are typically 2mm for a pigmented skin lesion, and up to 10mm for a melanoma.
For example, take a typical 8mm mole that is suspected to be a melanoma. Adding 2mm margins gives you a 10mm defect. The scar will therefore be 30mm to 40mm long.
Many people are surprised that excision of an 8mm lesion leaves a scar up to 4cm long.
What are the risks of surgical excision?
- Infection: around 5% but depends on a number of variables (age, medical problems, medications, type of procedure, climate – North Queensland has a significantly rate of wound infection)
- Bleeding: usually 20 minutes of firm pressure over an absorbent material will stop bleeding
- Wound deshiscence (the wound coming apart) eg following bleeding or infection
- Minor risks: swelling (seroma – clear fluid or ooze under the skin), suture allergy
- Rare risks: reaction or allergy to local anaesthetic (with or without adrenaline)
- Longer term risks: Hypertrophic scar is excessive but normal scar tissue. Keloid scar is scar tissue that continues to grow outside the wound edge. Keloid is most likely to occur on the front of chest, shoulders, ear lobes. Some people are genetically prone to keloid scarring. Keloid is more common in Asian, Black & Hispanic people.
When should stitches be removed?
A rough guide only (it is an individual decision depending on factors such as ease of closure, age of patient & how physical the person will be afterwards)
- Face 5 days
- Scalp: 7 to 9 days
- Trunk & Back: 10 to 14 days
- Legs and feet: 14 days or longer
- upper limbs: 8 to 14 days
Early removal of sutures will reduce risk of suture scars – but only if the wound is not under tension. Suture is left in for the shortest time on the face. The legs require suture to remain in placed for longer because of movement and tension of the skin.
How should I care for the wound?
The wound is only at 10% of final strength at 2 weeks, and 50% at 4 weeks. Healing wounds are delicate and need to be respected!
The key is to keep it covered until the removal of the sutures. It’s proven that moist wounds heal faster and better than dry wounds. The old adage of “getting air to the wound” is not appropriate! Typically, a clean dry dressing may be put on and replaced when required until suture removal.
It’s a good idea not to over-do the physical activities soon after the procedure, particularly for complex closures or excisions on the limbs or back. Come to an agreement with your doctor and stick to it!
After the sutures are removed, it is proven that “taping” the wound for up to 3 months reduces scarring. This is particularly important in areas where the scars tend to spread over time eg the back. How do you tape the wound? Just use steristrips or fixomull tape from the pharmacy, cut to size and put over the wound. Fixomull is a breathable fabric that sticks to skin that you can buy from a pharmacy.