American Melanoma Institute · 5 min read
How scraping, freezing, and simple excision treat low-risk skin cancers and precancers, what healing looks like, and when doctors avoid them.
Many skin cancers are treated in a regular exam room in under half an hour. Dermatologists rely on 3 procedures for this work: electrodesiccation and curettage, cryotherapy, and simple excision. Each suits a particular kind of growth, and each has places on the body and tumor types where doctors avoid it.
Dermatologists often shorten the name to ED&C. After numbing the skin, the doctor scrapes the tumor away with a curette, a pen-sized tool with a sharp loop at the tip. Skin cancer tissue is soft and crumbly compared with healthy dermis, the thicker layer under the surface, so the doctor can feel where the tumor ends.
Next the base is touched with an electric needle, which stops bleeding and destroys a thin zone of cells beyond the scraped area. The scrape and cautery cycle is often repeated once or twice in the same visit. The wound heals without stitches.
The American Cancer Society describes ED&C as an option for basal cell cancers confined to the top layer of skin with a low risk of returning, and doctors also use it for squamous cell carcinoma in situ. The Skin Cancer Foundation cites cure rates close to 95% for small basal cell carcinomas. Tell the doctor if you have a pacemaker or implanted defibrillator, because some electrosurgery devices can interfere with them and a heat-only cautery can be used instead.
Cryotherapy uses liquid nitrogen, which boils at minus 196 degrees Celsius. The doctor sprays it from a handheld canister, or dabs it on with a cotton-tipped applicator, for 5 to 30 seconds depending on how deep the freeze needs to go. Some lesions get a second freeze after the first one thaws. The cold stings and burns for a few minutes, and no anesthetic is needed for most spots.
Its main job is treating actinic keratoses, the rough, scaly precancers caused by sun. A dermatologist can treat many in a single visit. Cryotherapy can also treat small, superficial basal cell carcinomas and squamous cell carcinoma in situ, though the Skin Cancer Foundation puts its cure rate for basal cell carcinoma lower than surgery, between 85% and 90%. One advantage: it suits people with bleeding disorders or people who cannot tolerate anesthetic.
In a standard excision the doctor numbs the skin, cuts out the tumor with a margin of normal skin in a football shape, and stitches the edges together. The specimen goes to an outside lab, where a pathologist checks the edges. Results arrive in about a week.
Excision treats both low-risk and higher-risk tumors, and its written margin report sets it apart from scraping and freezing. The Skin Cancer Foundation gives cure rates above 95% for basal cell carcinoma in most body areas. If the report shows cancer at an edge, a second procedure follows, either another excision or Mohs surgery.
A cryotherapy site swells and turns red within hours, and a blister, sometimes blood-filled, often forms by the next day. The blister dries into a scab. DermNet, the New Zealand dermatology resource, gives rough healing times: 5 to 10 days on the face, about 3 weeks on the hand, and up to 3 months on the lower leg. Treated skin frequently heals paler than the skin around it, and the pale mark can be permanent. It shows more on darker skin.
An ED&C wound is a shallow, round sore. It heals from the bottom up over 2 to 6 weeks with daily cleaning, petrolatum, and a bandage, and lower leg wounds take the longest. The Skin Cancer Foundation describes the usual result as a round, whitish scar.
An excision leaves a line. Stitches come out in 1 to 2 weeks, and the scar reddens, firms up, and then fades over about a year.
Scraping and freezing share one weakness: no tissue edge goes to a pathologist, so no one confirms the tumor is fully gone. Doctors accept that trade for small, shallow, well-defined tumors on low-risk sites. They avoid it in these situations:
Hair-bearing skin such as the scalp and beard area is another weak spot for ED&C, since tumor can follow hair follicles below the depth the curette reaches. And if the curette breaks through into fat during the procedure, doctors generally switch to excision.
Cryotherapy should be used only when the diagnosis is known. Freezing an undiagnosed spot destroys the evidence a pathologist would need. People with cold-triggered conditions such as Raynaud disease or cold urticaria need a different approach.
Your biopsy report names the tumor subtype, and the subtype drives this choice more than any other single fact. Ask which subtype you have, whether the location counts as high-risk, and what the expected cure rate is for the option being offered compared with excision or Mohs surgery. Ask what the scar will look like in a year. A white circle on the shoulder bothers few people, while the same mark on the nose tip is another matter.
