Skin Surgery JC081: Skin Ulcers: Skin And Subcutaneous Lesions, Skin Cancer

Question 1

Skin and SC lesions

Answer 1

• Common
• Patients’ worries
  —> unknown nature
  —> malignancy
  —> appearance

Diagnosis:
- Sometimes obvious
- History + P/E follow
- Regional exam + Systemic review as indicated
- Lesion may represent an ***occult systemic problem

Question 2

History taking of Skin + SC lesions

Answer 2

1. Onset
2. Progression
3. Pain
4. Discharge / Bleeding / Ulcer

Question 3

P/E of Skin + SC lesions

Answer 3

1. Site, Size, Shape, Colour
2. Consistency, Surface, Border
3. **Tenderness, **Temperature (infection, inflammatory)
4. ***Pulsatility, Emptying (vascular lesion)
5. ***Skin / Deep fixation
6. ***Transillumination (cystic lesions)

Question 4

Management of Skin + SC lesions

Answer 4

1. Observation / Reassurance
2. Excision / Destruction (e.g. shave, liquid N2)
3. ***Excisional biopsy (suspicious lesions)
4. ***Incisional biopsy +/- Definitive treatment (unknown nature)
5. ***Wide excision +/- Reconstruction (malignant lesions)
6. Radiotherapy

Question 5

Skin structure

Answer 5

1. Epidermis
   - 3-5 cells thick
   - Impermeable stratum corneum
2. Dermis
   - 0.8-2.5mm thick (depends on location)
   - fibrous + tough
3. Hypodermis
   - indistinct loose fibrofatty layer
   - contains ***adnexal structures (vessels, hair follicles, sebaceous glands, sweat glands)
4. SC fat

Question 6

***DDx of Skin + SC lesions

Answer 6

1. Epidermis
   Benign:
   - Skin tags
   - **Warts
   - **Seborrhoeic keratosis
   - ***Keratoacanthoma

Premalignant:
- Solar keratosis
- Bowen’s disease
- Erythroplasia of Queyrat

Malignant:
- **SCC
- **Basal cell carcinoma

2. Epidermal-Dermal region (Melanocytic lesion)
   - Benign pigmented naevi
   - **Malignant melanoma (*lethal)
3. Dermis
   - Pyogenic granuloma
   - Histiocytoma
   - Keloid
   - Secondary carcinomas
   - Kaposi’s sarcoma
4. Skin appendages
   - **Epidermoid (sebaceous) cyst
   - **Dermoid cyst
   - Pilonidal sinus
   - Benign appendage tumour
5. Hypodermis / Deeper tissues
   - Lipoma
   - Liposarcoma
   - **Neurofibroma + Sarcoma
   - **Neurofibromatosis
   - Schwannoma
   - Deeper lesions e.g. ganglion
6. Vascular origin
   - Campbell de Morgan spots (aka Cherry angioma, Senile haemangioma)
   - Spider naevi
   - Angioma
   - Glomus tumour of digits

Question 7

Verruca vulgaris (Common warts) (+ SpC Revision)

Answer 7

• Multiple papular skin-coloured lesions
• Irregular thickened keratinised (warty) top
• Caused by ***HPV
• Related to trauma, on hand / foot
• Contagious + often multiple
• Poor immunity —> Multiple viral warts
• Brown / gray with a rough surface (***Warty spikes)
• Plantar warts: **Flattened + **Painful
• Genital warts: Soft + **Fleshy (*Condylomata acuminata)
• Can recur after treatment

Treatment:
1. Heat cautery
2. Cryosurgery / Cryotherapy
3. Laser (CO2)
4. Surgery (for persistent / recurrent cases)

Question 8

Corn + Callouses

Answer 8

• Massive thickening of ***stratum corneum
• Due to chronic trauma / irritation
• Corn: ***smaller, well marginated, square-shouldered
• Callouses: ***larger, more diffused, slope-shouldered
• Management: removal of irritation, paring, keratolytic agent (10-20% ***salicylic acid)

Question 9

Common cystic lesions (+ SpC Revision)

Answer 9

1. Epidermoid cyst (Sebaceous cyst)
   - true cyst (epithelial lining)
   - ?hair follicle origin
   - spherical, **attached to skin (always **mobile), overlying **punctum
   - contains cheesy **keratin material **NOT sebum
   - may get **infected (red, swollen, tender)
   - multiple: consider ***Gardner’s syndrome (associated with osteoma, fibromas, intestinal fibromatoses, lipomas, leiomyomas, polyposis coli)
   - complications: infection, sebaceous horn (sebaceous content keep forming without being removed then dried up)
   - management: Excision
2. Implantation dermoid
   - epidermal fragment (by penetrating injury) driven into dermis
   - lined by **epidermis producing keratin material
   - contains white amorphous material
   - tensely cystic (continuous proliferation of epithelium)
   - history of **trauma + presence of scar
   - common sites on fingers
   - management: Excision (to avoid infection)
3. Other epidermoid cysts:
   Milia
   - small 1-2mm epidermoid cysts on ***face

Pilar cyst
- trichilemmal cyst / wen
- ***slow-growing firm cyst on the scalp

Steatocystoma multiplex
- true sebaceous cyst —> contains ***sebum

4. **Dermoid cyst (sequestration dermoid)
   - **congenital cystic lesions growing slowly
   - occurs at ***embryonic fusion line regions (e.g. midline of scalp, external angle of eye, lower mandible)
   - contains keratin, hair, sebaceous glands etc.
   - management: excision

Question 10

Keratotic lesions (+ SpC Revision)

Answer 10

1. Seborrhoeic keratosis (Basal cell papilloma / Seborrhoeic wart / Senile wart)
   - common in **elderly
   - **brownish-black, raised, well-marginated
   - **plaque-like papules, “stuck-on”, square-shouldered
   - feels **waxy + irregular
   - proliferation of ***basal cells of epidermis
   - face, neck, chest wall
   - management: observe, cryotherapy, curettage, shaving, excision
2. Actinic keratosis (Solar keratosis, Senile keratosis)
   - **sun-damaged skin by UV, in exposed parts
   - dry, scaly, crusty top, erythematous based
   - early lesions: flat, roughened / scaly papules (which could just be palpable)
   - hyperkeratosis + acanthosis (i.e. thickening of skin) —> **pre-malignant
   - excision
   - if multiple: excision, curettage, cryosurgery, 5FU creams
3. Keratoacanthoma (Molluscum sebaceum)
   - from squamous cell of hair follicles
   - same area as BCC
   - can be **indistinguishable from BCC
   - **dome / nodular-shaped, flesh-coloured
   - **central crater filled with **keratin plug (Look like tumour central ulceration)
   - natural history: **rapid growth for a few weeks —> static for a few months —> **involution spontaneously, leaving an ugly scar
   - ***?variant of SCC
   - management: excisional biopsy, ?observation, ?RT

Question 11

Naevi

Answer 11

Developmental abnormalities: Hyperplasia of incompletely differentiated tissue elements

Types:
1. Melanocytic naevus (Mole)
2. Strawberry naevus (Infantile haemangioma)
3. Sebaceous naevus (Naevus of Jadassohn)

Question 12

1. Melanocytic naevus (Mole)

Answer 12

• Very common, benign
• Depends on location of naevus cells:
  1. Junctional (child, flat, darkly pigmented)
  2. Compound (younger adult, raised, variable pigmentation)
  3. Intradermal (older adult, dome-shaped, deep seated, lighter / flesh-coloured)
  4. Congenital (giant / hairy) (big, hairy, dark, raised, thick (**risk of malignant change))
  5. **Dysplastic
• uncommon in Asians, usually multiple, occasionally solitary
• irregular border + speckled pigmentations
• 2 major groups:
  —> Sporadic: Caucasians, fair skin, poorly tanned, excessive sunlight exposure with freckles etc.
  —> Familal: Dysplastic naevus syndrome, run in families, uncommon, up to 400x lifetime risk of malignant change
  6. Others (blue, Spitz, halo etc)
• risk of malignant changes very small except:
  —> Dysplastic naevus (esp. with family / personal history)
  —> Giant congenital melanocytic naevus (“bathing trunk”, life-long surveillance)
  —> >50, >2mm size
• DDx: **Melanoma, **BCC, ***Seborrhoeic keratosis
• when in doubt —> Excisional / Incisional biopsy

Question 13

Dermatofibroma (Histiocytoma, Sclerosing angioma)

Answer 13

• Firm skin nodule, 0.5-3 cm
• Fibrosis + Vascularity + Fe pigmentation
• Benign
• ***History of trauma / insect bite
• Deep reddish-brown
• ?Histiocytic origin
• DDx: ***Dermatofibrosarcoma protuberans (malignant)

Dermatofibrosarcoma protuberans (DFSP)
- **locally aggressive
- painless, indurated plaque with irregular nodules
- skin-coloured, border not well defined
- ?fibroblastic origin, ?malignant variant of DF
- infiltrative histologically with cords / nests of cells invading into adjacent soft tissue
- prone to **local recurrence, **seldom metastasise
- management: **wide excisional margin +/- RT

Question 14

Neurofibroma

Answer 14

From supporting ***fibroblasts of peripheral nerves
(- Neurilemmoma = Schwannoma (from neurilemmal cells, encapsulated, lobulated firm tumour))

1. Solitary:
   - SC, **tender, **firm nodule, ***mobile laterally
2. Multiple:
   - sessile / pedunculated, skin-coloured / brownish, well-circumscribed

Question 15

Neurofibromatosis

Answer 15

• AD inheritance
• NF-1, NF-2 (depending on clinical features, genes)
• Multiple lesions of different sizes, ***cafe au lait pigmentations
• ***Acoustic neuroma (type 2)
• deformities / disfigurement
• **possible malignant change
  (- **Plexiform NF: skin thickened with foldings, myxfibromatous degeneration, sporadic / familial)

Question 16

Lipoma (+ SpC Revision)

Answer 16

• commonest SC benign condition
• **SC lump / mass (1-20cm) —> **Can pinch skin over lipoma
• **Soft, **smooth surface with ***lobulations + encapsulated
• Diffuse / Well-defined lobulated mass
• Diffuse: ***Madelung’s disease (extensive + big lipoma in nape of neck, upper back in chronic drinkers)
• ***matured fat cells in thin fibrous capsule, grouped into lobules by vascular connective tissue septal
• big lipoma: may be ***soft + fluctuant
• management: conservative, excision, liposuction
• potential malignant change: ***Painful, Rapidly enlarging, Skin changes, Firm consistency may indicate malignancy (sarcomatous changes)

Question 17

Vascular anomaly

Answer 17

1. Vascular tumours
   - Rapid proliferating vascular endothelium
   - usually **not present at birth
   - rapidly ↑ in size
   - may involute
   - F:M = 3:1
   - 60% head and neck
   - **most common tumour of infancy
   - “strawberry naevus” (NOT a naevus but vascular tumour)

Types:
- Benign
- Locally aggressive / Borderline
- Malignant

2. Vascular malformations
   - Congenital abnormal vascular anatomy + morphology
   - **present at birth (but may not be clinically apparent)
   - **grow in proportion to body size
   - can degenerate but also can hypertrophy (AVM)
   - ***Fast flow (e.g. Arterial) vs Slow flow
   - diagnosis by history + P/E
   - adjuncts: USG, MRI, Angiography

Types:
- Simple (Capillary / Lymphatic / Venous / ***Arteriovenous / Arteriovenous fistula)
- Combined

Question 18

Infantile hemangioma (Strawberry naevus)

Answer 18

• NOT Congenital haemangioma!
• Bright red haemangioma, in baby
• appears shortly after birth —> rapidly grows for a few weeks to months —> static for some time —> involution
• residual redundant skin / scar common

Management:
1. Observation
2. **Steroid, **β-blocker
3. Laser, Excision

Question 19

S/S of Vascular tumours

Answer 19

Intrinsic:
- **Bleeding
- **Ulceration
- ***Kasabach-Merritt syndrome (Thrombocytopenia associated with kaposiform, haemangioendothelioma NOT common Haemangioma)

Extrinsic:
- Upper eyelids
—> deprivation **amblyopia (弱視) + failure to develop binocular vision
—> corneal distortion + astigmatism
- **Airway obstruction (if grow in airway)

Question 20

Vascular malformations

Answer 20

1. Arterial: Fast flow e.g. AVM
   - **Schobinger staging of AVM
   Stage 1: A blue-skin blush
   Stage 2: A mass associated with a bruit + a thrill
   Stage 3: A mass associated with ulceration, bleeding, pain
   Stage 4: Stage 3 lesions decompensation producing heart failure
   - Management: Pre-op **embolisation +/- Complete excision
2. Venous
   - Slow flow
   - Management: Debulking, ***Sclerotherapy
3. Capillary
   - e.g. ***Port-wine stain (on face)
   - Management: Laser
4. Lymphatic
   - Macrocytic vs Microcytic
   - e.g. primary **lymphedema, **cystic hygroma
5. Combination
   - e.g. Klippel Trenaunay Syndrome, Parkes Weber syndrome

Question 21

Port-wine stain

Answer 21

• Capillary malformation
• Present at birth, often on ***face / scalp
• Flat / slightly elevated, ***reddish-blue to purplish
• Advancing age —> thicker + nodular + hypertrophy
• Associated with intracranial haemangioma —> DDx: ***Sturge-Weber syndrome

Question 22

Cystic hygroma

Answer 22

• Collection of ***lymphatic sacs containing lymph
• Failure of fusion of lymphatic channels
• Present at birth (some later)
• Usually root of neck, axilla, groin
• **Soft, fluctuant, markedly **transilluminating
• Management: Excision

Question 23

Skin tags (Papilloma)

Answer 23

• More in advanced age
• Benign
• Proliferation of epidermis
• Often multiple, 1-5 mm
• Loose CT core with normal covering ***squamous epithelium (pigmented / keratinised)
• Management: Excision, Laser

Question 24

Cutaneous horns

Answer 24

Descriptive term for any protuberant horny skin growth
- usually conical projection of ***keratinised material

Pathologically may be pre-malignant / benign / malignant:
1. **Actinic keratosis (with / without underlying SCC) (pre-malignant)
2. **Seborrhoeic keratosis (benign)
3. ***SCC (malignant)

Management:
- Biopsy to confirm Dx + remove the horn

Question 25

Pyogenic granuloma

Answer 25

• Benign condition
• aka “Eruptive Haemangioma”
• Induced by ***trauma
• ***Red, fleshy, spherical nodule —> looks like a vascular tumour
• **Rapid + excessive growth of granulation tissue rich in **blood vessels + inflammatory cells
• **Ulcerate + **Bleed easily —> complaining of bleeding
• Management: Excision, Curettage, Diathermy of base

Question 26

Xanthelasma

Answer 26

• Deposition of ***lipid-laden macrophages in the superficial dermis
• Soft, flat-topped yellow papules, may coalesce
• Usually starts at upper eyelid near the medial canthus
• About 1/3 of patients have hyperlipoproteinaemia
• Management: Excision (may recur)

Question 27

Benign tumours of Epidermal appendages

Answer 27

1. Hair follicle
   - Trichofolliculoma
   - Trichoepithelioma
   - Pilomatrixoma
   - Trichilemmoma
2. Sebaceous gland
   - Sebaceous adenoma
   - Adenoma
3. Sweat gland
   - Cylindroma
   - Synringoma

Some have typical appearance, otherwise Dx confirmed on ***Histological exam

Question 28

Pre-malignant skin conditions

Answer 28

1. **Bowen’s disease, **Paget’s disease of nipple
2. ***Xeroderma pigmentosa, Albinism
3. Chronic unstable scar / Destruction of skin
   - Chronic radiation dermatitis
   - Burn scar / Chronic osteomyelitis
   - ***Actinic keratosis

Question 29

Bowen’s disease (***Squamous carcinoma-in-situ, Intraepidermal epithelioma)

Paget’s disease of nipple

Answer 29

Bowen’s disease (**Squamous carcinoma-in-situ, Intraepidermal epithelioma)
- Dysplastic cells confined to basal lamina (without definite invasion)
- Thickened, reddish-brown, scaly patch with irregular border
- If in penis: **Erythroplasia of Queyrat with velvety-red plaque like appearance
- Management: Excision, **RT, **Topical 5FU, Cryotherapy, Photodynamic therapy

Paget’s disease of nipple:
- Paget cells arise from **mammary ducts to the nipple epidermis
- **Erythema + ***Eczematous lesion of nipple —> Erosion + Ulceration
- 50-60 yo
- 97% has underlying breast carcinoma, ~50% present with breast mass
- Diagnosis: Incisional biopsy
- Management: Treat underlying CA breast

Extramammary Paget’s disease (EMPD)
- ***Peno-scrotal area / Axilla area
- Intraepithelial adenocarcinoma
- Associated with underlying malignancy e.g. Prostate, Colon —> Need to screen
- Management: Wide excision + Treat underlying malignancy if any

Question 30

Common malignant skin cancers

Answer 30

Most common —> less common:
1. Basal cell carcinoma (BCC)
2. SCC
3. Malignant melanoma

Question 31

1. Basal cell carcinoma (BCC) (+ SpC Revision)

Answer 31

• Due to ***excessive sunlight (UV) exposure
• ***Commonest skin cancer
• ***Low grade malignancy
• ***Middle age / Elderly
• Originate from ***basal epidermal cells (?pilosebaceous unit), slow growing
• **Face / scalp / **neck / dorsum of hands / forearms
• Also in patients: XP (xeroderma pigmentosum), ALB (albinism), Naevoid basal cell carcinoma syndrome, Sebaceous naevus (congenital lesion predisposing patients to BCC)
• Multiple lesions are common
• **Locally invasive, **slow growth, ***seldom metastasise
• ***Serous discharge / bleeding, may be pigmented

Clinical types:
1. ***Pigmented (common in orientals)
2. Nodular / Nodular-ulcerative
3. Superficial
4. Cystic
5. Morphreaform (sclerosing)

Features:
- Typical ulcer: **Rolled edge + “cystic lesion” with **pearly white edge + ***telangiectasia + central ulceration (Rodent ulcer)
- Seldom spread to regional LN / by blood
- Most lesions are well localised

Management:
1. Excision with margins (2-3 mm) (**3-5 mm (SpC Revision)), **RT, 5FU cream
2. Cryotherapy, cauterisation, electro-desiccation should be used with ***much caution

Beware of lesions: Post-op / RT recurrence
- Medial canthus (眼角)
- Peri-alar
- Preauricular
- Morpheaform type (∴ need a wider excision margin)-

Question 32

2. Squamous cell carcinoma (SCC) (+ SpC Revision)

Answer 32

• Mostly a result of ***excessive sunlight (UV) exposure
• Less common but **more malignant than BCC + **more rapid growth
• Arise de novo / in pre-existing skin lesion
• May develop from ***Actinic keratosis
• Other causes: Carcinogens (RT, **arsenic, chromium compounds, soot, tar), Chronic **non-healing wounds, Unstable scars
• Congenital diseases: XP, ALB
• Immunosuppression: Diseases, Therapy

Clinical features:
- **Everted edge / Exophytic growth
- **Irregular ulcer (e.g. **Marjolin’s ulcer: malignant ulcer that develop over chronic wound, usually in sacrum / venous ulcer in ankle)
- **Indurated base + fixed to underlying structure
- Evidence of sun-damage skin lesions
- **More aggressive: metastasis by **lymphatic (examine LN) + ***haematogenous route

Investigation:
- Biopsy from ***edge of ulcer

Management:
- Wide excision (10-15mm from Goddisk) +/- Reconstruction (∵ **larger excision margin)
- **Block dissection for LN metastasis (e.g. axillary dissection)
- RT

Question 33

3. Malignant melanoma (+ SpC Revision)

Answer 33

• Malignant tumour of ***melanocytes (mesodermal) (normally located in basal layer of epidermis)
• Cutaneous ones induced by ***sunlight (UV)
• Arise de novo / from pigmented nevus
• Less common than BCC, SCC
• Other sites: mucous lining, **choroid of eye, meninges, soft tissues (*amelanotic melanoma: no melanin production —> skin colour / erythematous colour

Signs of malignancy in benign nevus:
1. Increase in size
2. Increase / Decrease in pigmentation
3. Ulcerate, weep, bleed
4. Itchy / burning sensation
5. Spread of pigmentation
6. LN enlargement
- Any suspicion —> Biopsy

(From CFB14: Mnemonic (ABCDE):
- Asymmetry: Irregular shape
- **Border: Ragged outline
- Colour: Variation
- Diameter: >6mm across / recent increase in size
- **Elevation: Raised above surface of skin
- Evolution: changes in size, colour, shape over time)

Features:
- **Aggressive: metastasis to **LN (Satellite / In-transit lesions; Regional / Distant LNs) / by **blood
- Most are **darkly pigmented lesions
- Recent onset / change in pigmentation of pre-existing lesion, irregular border / appearance
- Increase in size, bleeding, loss of hair

5 Clinical types:
1. Superficial spreading
2. **Nodular (most aggressive, invade deep in SC tissue early)
3. **Lentigo maligna melanoma (least aggressive, face, nailbed)
4. Acral lentiginous melanoma (hand / foot)
5. Subungal melanoma (nail)

Grading system:
1. **Breslow scale (thickness) (more favoured for less observer’s variability)
2. **Clark’s level of invasion (level 1-5)
—> guide treatment + prognosis
—> both correlate with LN metastasis + survival
—> Thinner lesions —> Better prognosis

Management:
1. Surgery
- Only treatment method for potential cure
- Excision margin: depends on ***Breslow’s thickness (i.e. depth of invasion), range from 1-3 cm

2. SLNB
   - For intermediate thickness tumour (e.g. 1-3 mm) —> carries **prognostic information + facilitate **staging
3. Regional LN dissection
   - Improves nodal control but ***NOT survival
4. Block dissection
   - For LN metastasis if no distant metastasis
   (- ?Role of elective block dissection in intermediate thickness tumour)
5. Others
   - Hyperthermia + Isolated limb perfusion for in-transit metastasis in specialised centre
   - Systemic chemotherapy ***not useful
   - Immunotherapy (control lesion + prolong survival): Anti-PD1 (Pembrolizumab, Nivolumab) (SpC PP)

Question 34

Uncommon malignant tumours

Answer 34

1. Merkel cell carcinoma
2. Skin appendageal carcinoma
3. ***Sarcoma
4. Malignant nerve sheath tumour
5. Angiosarcoma
6. ***Lymphoma
7. ***Metastatic tumour

If not sure —> biopsy

Question 35

Benign skin tumours vs Malignant skin tumours

Answer 35

Benign skin tumours:
- In young patients except Melanoma, Sarcoma

Features:
- Remain static in size / grow in proportion with patients
- **Do NOT ulcerate / bleed
- **Well defined regular border
- Can be raised / flat
- No enlarged regional LN

Malignant skin tumours:
- More common in elderly
- **Grow in size
- **Arise from pre-existing lesions e.g. naevus, scar
- **Ulcerate / Bleed
- **Irregular / poorly defined border
- **Raised
- Enlarged regional LN
- **Satellite lesions (e.g. malignant melanoma)

Question 36

Ambulatory Surgery: Skin lesions (SpC FM)

Answer 36

Keratosis = Growth of keratin on the skin or on mucous membranes stemming from ***keratinocytes, the prominent cell type in the epidermis (wiki)

Seborrhoeic keratosis (Senile wart):
- Benign
- Old age
- Pigmented, dry keratin (dead cell from the top layer of epithelium)
- Rough surface
- Raised
- Does not bleed when cut open

Actinic / Solar / Senile keratosis:
- Premalignant (SCC)
- Sun exposed
- Does not bleed when cut
- More living cells from deeper layers of epithelium

Dermoid cyst:
- Congenital: lateral eyebrow
- Usually in midline??
- Looks like lipoma
- Acquired: on hand due to trauma

Sebaceous cyst (Epidermoid cyst):
- From dermis layer, not able to pinch skin???
- Smooth not pedunculated
- Half have punctum
- Tense consistency

Papilloma (aka Skin tag):
- Prominent, round +/- pedunculated
- If small, equivalent to skin tag
- Fleshy, skin coloured
- Living cells when cut, will bleed

Neurofibroma:
- Buttonhole sign
- Tender, firm nodule, mobile laterally

Dermatofibroma:
- Buttonhole sign

Mole / Nevus:
-Canberaised
- DDx: Melanoma, Seborrhoeic keratosis, BCC

Question 37

Mucus retention cyst (SpC Revision)

Answer 37

• Obstruction of an excretory duct leading to back pressure of mucus + formation of an epithelium lined cyst
• Minor trauma leading to rupture + escape of mucus into tissue —> recur afterwards
• Smooth, transparent lesion

Question 38

Choice of anaesthesia

Answer 38

Indications:
- Biopsy / Examination / Surgery

Local anaesthesia:
- Small lesions
- Superficial lesions
- Single lesion
- Cooperative patients
- Prolonged operation / Complicated procedure

Lignocaine (1% / 2% / +/- Adrenaline):
- Max dose:
—> Without adrenaline: 4 mg/kg
—> With adrenaline: 7 mg/kg
- Duration of action: ~1.5 hours —> May give additional dose

1% Lignocaine = 10 mg/ml

Example:
60kg patient:
- 1% lignocaine: 4 x 60 / 10 = 24 ml
- 1% lignocaine with adrenaline: 7 x 60 / 10 = 42 ml

Systemic toxicities:
CNS:
Early:
- Tinnitus
- Blurred vision
- Dizziness
- Tongue parasthesia
- Perioral numbness

Late:
- Slurred speech
- Drowsiness
- Seizure
- Respiratory arrest

CVS:
- Sinus bradycardia (prolonged PR, widened QRS)
- Ventricular arrhythmia
- Hypotension
- Cardiac arrest

Avoid systemic toxicities:
- Proper injection: Avoid IV injection
- Proper dosage

Treatment of systemic toxicities:
- Stop LA injection
- Call for help
- Airway
- **Control seizure by BDZ
- Treat hypotension / bradycardia (CPR if pulseless)
- **20% lipid emulsion bolus (1.5 ml/kg) then infusion (0.25 ml/kg/min): Max dose: 12 ml/kg