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Dermatologic Procedures

Toby Maurer, MD

University of California, San Francisco

• Liquid nitrogen

• Intralesional steroids

• Unna Boots

• Biopsies-snip, shave, punch

• …..scabies prep and KOH preps

The Gun vs. The Q-Tip

• Cost:

• Gun delivers more constant pressure

• Gun is faster if you have the volume

Liquid Nitrogen

• Thaw time is key

• Thawing destroys the cells

• Freeze to get sustained ice ball & adequate thaw time

• Thaw time - From time the lesion is white until it goes back to normal color

• Always do 2 cycles of thawing

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Liquid Nitrogen (cont’d)

• Thaw times differ by location

– Face/genital 2 x 15 sec. thaws and dorsal arms

– Palms/soles 2 x 30-45 sec. thaws

• Thaw times differ by diagnosis

– Seborrheic keratoses - 15 sec. thaws

– Actinic keratoses - 15 sec. thaws

– Warts - need more & want to go 1mm around periphery

Know what you are freezing

• Check that pt has resoltuion of lesion-document that you told them or that you are bring them back

Side Effects

• So cold it feels like a burn

• Blister tonight then crust that will take 5 days to resolve (15 sec. thaws) vs. 10 days (30-45 sec. thaws)

• Can break the blister

• Warn re: hypo/hyperpigmentation in persons w/underlying pigment

Intralesional Steroids

• Used for keloids, hypertrophic scars, patches of alopecia areata

• Trick is not to go into fat but stay in dermis(don’t want atrophy)

• Warn patient and document potential side effects like pigment change and atrophy

• For alopecia areata -10 mg/cc; 1-3 cc per month

• For Keloids-20-40 mg/cc; 1 cc per month

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Keloids

• Intralesional steroids-20-40 mg/cc

• Pts will absorb steroids systemically so limit is 40 mg per month

• Anaesthetize surface with lidocaine and epinephrine using 30 gauge needle

• Get into the right space and inject steroid with 22 gauge needle

How to do a KOH

• Scrape the area and GET LOTS of scale-use a 15 scalpel

• Place cover slip on top of scale

• Put a drop of KOH on the side of the cover slip and let it go under the slip by osmosis

• Heat the specimen not to point of boiling (Important to do when you have dry skin)

• Use your pen to put pressure on cover slip to separate the cells

• Bring your condensor all the way down

• Use 4x power and MAX of 10 x power to look for hyphae

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Scabies Prep

• Why do it? Not everything that itches is scabies Tip: itchy nodules on penis=scabies

• Don’t rely on finding a burrow but if you do, scrape it-high yield

• Highest yield areas-between the fingers, wrists, scapula, lateral edge of the feet-look for papulovesicular lesions that are primary (not scratched)

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Juice and scale go on slide, place cover slip on top

Mineral oil is great but water will do

Bring condenser all the way up

Look at every part of slide and especially around cover slip edges

Unna Boots

• For venous ulcers when there is edema

• Make sure there is no cellulitis before you cover an area

• You will need:

Currette, +/- lidocaine (no epi), metrogel, duoderm, allevyn, unna boot

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Unna Boots

• Never too tight

• Leave folds in place

• Anchor joints

• Start at mid foot and work up to the knee

• Coban layer on outside

• If pt notes pain, take dressing off

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BIOPSIES

• Pathologists are only as good as the clinician

• REFER - If you have no idea what you are looking at, neither will the pathologist.

• Must include history, location and DIFFERENTIAL diagnosis-what are you ruling out AT LEAST

Biopsy Tips

• Give your pathologist an adequate and representative sample

• Choose a lesion that has not yet evolved

• Don’t crush the tissue

• If your results don’t make sense, call the pathologist or a dermatologist for review

• Billing: procedural code for biopsy (including closure)-neoplasm of uncertain behavior

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• NUMBING IS STANDARD OF CARE

• 1% Lidocaine and epinephrine

• Epi-okay to use on fingers, toes, and penis unless using large doses

• Do not use Epi in Reynauds or other vascular problems (lower leg vascular insufficiency)

• EMLA in Kids followed by IL numbing

• Lidocaine allergy

• IL Benadryl

Informed Consent

• Why are you doing this?

• What could be done instead?

• Risks involved

– Scar

– Infection

– Bleeding

Snip Biopsies/Excision

• Scissor snip

• Skin tags

• AlCl for hemostasis

• Send to pathology

• Do NOT use silver nitrate or Monsels on visible skin

Shave Biopsies

• Leave half of lesion behind so you know to where to return for definitive treatment

• Puff up section with anesthetic and LIGHTLY pick up with forceps-scalpel cuts under skin

• Al Cl for hemostasis

• Petroleum jelly/bandaid

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Punch Biopsies• Allows you to get to the top of the fat

• You will get the epidermis and dermis

• Use for diseases that go into the dermis from the epidermis or that originate in the dermis. (Hint: There is a palpable or papular/ nodular component.)

Punch Biopsy

• Punch (sizes 2-6mm)

– 2mm - Not enough info for pathologist

– 3 mm - Use in cosmetically sensitive areas

– 4mm - Standard

– 5-6mm - Use to get around lesion or if submitting part of a biopsy for tissue culture

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Punch Biopsy - You Will Need

• Non-absorbable suture

– 2mm & 3mm - one stitch

– 4mm - two stitches

– 5mm and 6mm - three stitches

– GELFOAM

How to make a hole oval?

• All in skin tension lines

Suturing

• Interrupted adequate

• Double knot for first throw then 3 more single knot throws

• Remove sutures in 3 days face, 7 days back, chest and 10-14 days limbs

• Petroleum jelly/bandaid-keep wound dry

Excisional Biopsies

• You have control

• Go down to fat, through fat to fascia & beyond

• Lets you get around the lesion entirely

– Malignant melanoma

– r/o Dysplastic nevus vs. malignant melanoma

– Vasculitis

– Panniculitis

– Epidermoid cysts

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• Mark it with pen before putting in anesthetic

• 3:1 rule-measure lesion- If 1 cm, then will need total length to be 3 cm (1.5 cm on each side) for proper closure

3 cm

1 cm

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• Don’t bevel blade-should be perpendicular

• Undermine edges for larger wounds-helps to close