S&P Lecture 8: Derm (Punch and Shave Biopsy)

Why do we perform derm procedures? (select all that apply)

1. Identify or confirm lesions/rashes (especially malignant) 2. Remove symptomatic lesions (itchy, painful, rubbing on clothing) 3. Remove biopsy-proven malignancies 4. Narrow down the treatment plan 5. Cosmetic removal 6. Because we have no clue what something is

What are the contraindications to derm procedures? (select all that apply)

1. No consent 2. True anesthetic allergy 3. Infected site 4. Uncontrolled bleeding risk 5. Poor-healing site (lower leg + DM/PAD) 6. Keloid history

What are the steps of a derm procedure? (select all that apply)

1. Mark the lesion (and margins) 2. Photograph lesion with body identifiers and a ruler 3. Patient signs consent 4. Prep (alcohol pad) 5. Anesthetize (lidocaine) 6. Perform procedure 7. Place lesion in labeled container 8. Achieve hemostasis 9. Apply healing ointment and dressing 10. Discuss wound care (written instructions) 11. Verify requisition form

What 3 things must the requisition form contain? (select all that apply)

1. Location 2. Description 3. Rule out

Why must biopsy site labeling be very specific (e.g. 'right superolateral malar eminence' not 'right cheek')?

So the lesion can be found later without a picture or a scar from the biopsy

What margin is acceptable for a shave biopsy?

No formal margins - 1-2 mm of normal skin around the obvious lesion

What excision margin is needed for a low-risk basal cell carcinoma?

4 mm (Mohs for high risk)

What excision margin is needed for a low-risk squamous cell carcinoma?

4-6 mm (high risk: Mohs or 6-10 mm)

What excision margin is needed for melanoma in situ?

5 mm - 1 cm

What determines the excision margin for invasive melanoma?

Breslow depth (tumor thickness)

What margin is needed for melanoma ≤ 1 mm deep?

1 cm

What margin is needed for melanoma > 1-2 mm deep?

1-2 cm

What margin is needed for melanoma > 2 mm deep?

2 cm

Which melanomas need a discussion about surgery with lymphoscintigraphy?

Any invasive melanoma ≥ 0.8 mm or ulcerated

Why should excisions ALWAYS follow skin tension lines? (select all that apply)

1. Reduces wound dehiscence 2. Reduces hypertrophic or keloid scarring 3. Prettier scar 4. Can hide the scar in a wrinkle or skin fold

What are the drawbacks of chlorhexidine prep? (select all that apply)

1. Irritates mucous membranes 2. Ototoxicity 3. Ocular toxicity 4. Decreased effect with blood/pus 5. Flammable 6. Chemical burn if occluded 7. Do not use on large wounds

Which skin prep is gentle, non-toxic, non-flammable, and broad spectrum (needs 30 seconds)?

Hypochlorous acid

What is the concentration of 1% vs 2% lidocaine?

1% = 10 mg/mL - 2% = 20 mg/mL (more risk)

A patient reports a lidocaine 'allergy' - what was the reaction most likely?

High heart rate from the epinephrine (true allergy almost never)

Why is lidocaine buffered with sodium bicarb?

Raises pH to less acidic levels = less sting

What is the ratio of bicarb to lidocaine when buffering?

1:10 (1 mL lidocaine = 0.1 mL bicarb)

What is the shelf life of buffered lidocaine without vs with epi?

1 week without epi - 1 day with epi

What are the benefits of adding epinephrine to lidocaine? (select all that apply)

1. Blood control 2. Lasts longer 3. Decreases risk of lidocaine toxicity (vasoconstriction reduces systemic absorption)

Per the lecture, what about the 'fingers, toes, penis, nose' rule for epi?

Real life: ignore it most of the time

What are the anesthesia options in pregnancy? (select all that apply)

1. Normal saline (must work fast) 2. Plain lidocaine (reduce dose) 3. Avoid bupivacaine

What are the neuro symptoms of lidocaine toxicity? (select all that apply)

1. Tinnitus 2. Dizziness 3. Mouth numbness 4. Metallic taste 5. Confusion 6. Seizure

What cardiac signs of lidocaine toxicity often come FIRST? (select all that apply)

1. Bradycardia 2. Hypotension 3. Palpitations 4. Arrhythmia

What is the treatment of LAST?

Stop procedure, call 911, activate ACLS (give epi)

What is the max dose of lidocaine WITHOUT epi?

5 mg/kg (max 300 mg = 30 mL of 1%) - e.g. 45 kg = 22.5 mL

What is the max dose of lidocaine WITH epi?

7 mg/kg (max 500 mg = 50 mL of 1% with epi) - e.g. 45 kg = 31.5 mL

How should lidocaine dosing change in older adults with severe liver or kidney disease?

Decrease total dose by ~50%

What is the max lidocaine dose for children < 8?

80% of max dose - 4 mg/kg without epi - 5.6 mg/kg with epi

What is the onset and duration of lidocaine without vs with epi?

Onset 2-5 min for both - duration 0.5-2 hours without epi - up to 3 hours with epi

How long does bupivacaine last?

Up to 6 hours

What is the most common biopsy technique?

Shave

What lesions are removed by shave? (select all that apply)

1. Seborrheic keratoses 2. Warts 3. Benign nevi

What is saucerization?

A deep, wide shave (NMSC, dysplastic nevi - melanoma with 1-3 mm margins)

Which closure methods are for linear low-tension wounds and skin tears in fragile skin (e.g. older adults)?

Tissue adhesives and wound-closure tapes

When should tissue adhesives NOT be used? (select all that apply)

1. Wound actively oozing blood 2. Hairy/moist areas (unless hair trimmed) 3. Wound under tension (unless splinted)

Which superficial suture has the BEST tensile strength but is slippery (needs 4-5 throws)?

Polypropylene (nonabsorbable)

Which absorbable suture is used on the face and in young children and holds only 4-6 days?

Fast-absorbing gut

Which deep (subcutaneous) suture holds 30 days and is braided?

Polyglactin

Which monofilament absorbable suture holds 7-10 days and is used for subcuticular closure of facial lacerations?

Poliglecaprone 25

In the USP suture system, what does a higher number of zeros mean?

Smaller size and lower strength

What skin suture size is used on the nose, vermilion border, or eyelid?

6-0

What skin suture size is used on the trunk/extremities under tension or across a joint?

3-0 or 4-0

Which biopsy is best for rashes, and why?

Punch - full-thickness view for the pathologist (epidermis, dermis, subQ fat)

How is a punch biopsy done for hair loss?

Two adjacent 4 mm punches placed in the same bottle

When should a punch be avoided?

Pigmented lesions - unless it is the nailbed or you can capture the whole lesion

Which punch defects can heal by secondary intention with gel foam?

< 4 mm

What is snip removal indicated for? (select all that apply)

1. Skin tags 2. Filiform warts 3. DPNs

Why does the lecturer recommend lidocaine with epi for all skin tags and filiform warts?

So you can use cautery (they have a good blood supply)

Where do APPs usually NOT do excisions?

Head or neck

What skin cancers can be excised by APPs? (select all that apply)

1. Dysplastic nevi 2. NMSC 3. MMIS 4. Melanoma < 0.8 mm deep and non-ulcerated

What is the #1 complication of derm procedures?

Bleeding

Who gets a pressure dressing, and how long is it left on?

All surgeries and anyone on blood thinners - leave in place 24 hours

Which blood thinners/supplements are flagged for bleeding risk? (select all that apply)

1. Baby aspirin 2. Fish oil 3. Vitamin E 4. Warfarin 5. Apixaban

How do you control in-office bleeding that won't stop?

Firm pressure for 5 minutes without peeking

What % of suspected post-procedure infections are NOT infected?

90% (always have them come back for evaluation)

What are the signs of a real wound infection? (select all that apply)

1. Increased pain 2. Dripping pus 3. Growing or streaking erythema 4. Very hot to the touch

What causes wound dehiscence? (select all that apply)

1. Edematous area of the body 2. Not following aftercare (using the muscles in the area within 2 weeks) 3. Poor wound care

Do patients need to pretreat with antibiotics or stop GLP-1s before a derm procedure?

No (unless their doctor insists on antibiotics)

What is often the FIRST symptom of a vasovagal reaction?

Cough

What are the symptoms of a vasovagal reaction? (select all that apply)

1. Cough (1st) 2. Diaphoresis 3. Pallor 4. N/V 5. Feels hot/dizzy/uneasy 6. Tunnel vision

What is the treatment of a vasovagal reaction? (select all that apply)

1. Stop procedure 2. Trendelenburg 3. Ice pack on the neck 4. Fan 5. Smell alcohol pad 6. Juice and snack

How are vasovagal reactions prevented (especially in teen boys)?

Snack policy

What should a wound be covered with after a procedure?

Plain ointment (petrolatum) and a bandage

A patient reacts to bandaid adhesive - is it a latex or adhesive allergy?

Neither - it is adhesive sensitivity (very common) - use sensitive/transparent film dressings

Why should topical neomycin, polymyxin B, bacitracin, or triple antibiotic NEVER be used on wounds?

Allergic/sensitivity reaction

Why should mupirocin NOT be used on post-procedure wounds?

Antibiotic resistance (these wounds almost never get infected)

What water should patients avoid while healing? (select all that apply)

1. Ocean 2. Lake 3. Hot tub 4. Community pool