Malignant Melanoma - Hyperexcision

Last updated: March 9, 2026

Melanoma is the proliferation of atypical melanocytes. It is the most dangerous type of skin cancer. Melanoma has a high potential to invade the dermis and metastasise. 70% of melanoma arises from normal skin, while 30% arise from pre-existing naevi. In women, they are common on the lower leg; they present sooner since women are more concerned about skin lesions. They commonly occur on the back in men. Survival is inversely correlated to the depth of invasion (Clark’s levels or Breslow thickness)

Melanoma accounts for only 1% of skin cancer, but it is a major cause of mortality from skin cancer. The peak age is 40 – 70 years old – it is still a significant cause of cancer in young individuals.

Types of melanoma

Type of melanoma	Description
Superficial spreading melanoma (65%)	Occurs on the face and neck (or other sun-exposed areas) in elderly patients. Typically a large, flat, dark lesion. Has the best prognosis
Lentigo maligna melanoma (15%)	Occurs on the face and neck (or other sun-exposed areas) in elderly patients. Typically, a large, flat, dark lesion. Has the best prognosis
Nodular melanoma (10 – 15%)	Occurs anywhere on the body, often dark coloured. May be pearly or lack pigment. Rarely metastasizes but grows rapidly in a vertical direction. This has the worst prognosis.
A rarer type common in Africans (dark-skinned individuals). Occurs on the palms, soles or subungal skin (under fingernails)	A rarer type common in Africans (dark-skinned individuals). Occurs on the palms or soles or subungal skin (under fingernails)

Growth of melanoma

Growth	Description
In situ	Tumour spreads into the dermis
Invasive	Tumur spreads into the dermis
Metastatic	Tumour spread to other tissues

Clark’s level (anatomic level of skin invasion)

Clark’s level	Description
Level I	Confined to epidermis (melanoma in situ)
Level II	Invades papillary dermis
Level III	Fills papillary dermis
Level IV	Invades reticular dermis
Level V	Invades subcutaneous tissue

Brewslow thickness (vertical depth of tumour in millimetres; it is the most important prognostic factor for localised melanoma)

Breslow Thickness (mm)	Tumor Category (T stage)	Prognostic Significance
≤ 1.0 mm	T1	Thin melanoma, best prognosis
1.01 – 2.0 mm	T2	Intermediate risk
2.01 – 4.0 mm	T3	Higher risk of metastasis
> 4.0 mm	T4	High risk, poorest prognosis

Risk factors for melanoma
- Sun exposure (not as significant as SCC or BCC)
- Male gender
- Advanced age
- Multiple naevia (> 50 is a significant risk)
- Family history of melanoma (p16 loss of function)
- Fair complexion
- Smoking
- History of melanoma or other skin cancer
- Dysplastic nevus syndrome (autosomal dominant)
Pathophysiology
- 50 – 70% of melanomas arise de novo; the rest present at the site of existing moles.
Physical examination
- Asymmetric
- Irregular Borders
- Variegated Color
- Diameter > 6mm
- Evolving
- Pigmented lesion
Differentials
- Benign melanocytic naevus (mole)
- Lentigines and ephelides
- Seborrhoeic keratoses
- Dermatofibroma
- Pigmented basal cell carcinoma
Investigations
- Dermoscopy to visualise the lesion
  - Atypical pigment network
  - Aggregated black or brown dots and globules
  - Parallel ridge pattern on palms and soles
- Full-thickness excisional biopsy (with narrow clinical margins)
  - Nests of melanocytes
  - Prominent nucleoli
  - Mitotic figures
  - Tumour marker S100
- Metastatic workup: whole-body and brain contrast-enhanced CT scan for stage IIB; staging CT for stage IIC to IV; brain MRI
Treatment
- Wide local excision – margins are guided by depth
  - Melanoma in situ: 5 mm margin
  - < 1mm depth: 10 mm margin
  - 1 – 4 mm depth: 10 – 20 mm margin
  - 4 mm depth: 20 mm margin
- Sentinel lymph node biopsy
  - For melanoma with Breslow thickness of 0.8 – 1.0 mm with ulceration, lymphvascular invasion or mitotic index of 2 or more
  - For melanoma with a Breslow thickness > 1.0 mm
- Targeted therapy with BRAF and MEK inhibitors
- Immunotherapy – anti-PD-1 +/- CTLA-4 therapy – for advanced disease
- Chemotherapy or radiotherapy for advanced lymphoma
Complications
- Local tissue invasion and destruction
Prognosis
- Prognosis is based on the depth of dermal invasion (Breslow depth) for local melanoma
  - Breslow depth measures the uppermost cell in the stratum granulosum down to the lowest abnormal cell

Reference Intervals ›

Biochemistry

ACTH	P: <80 ng/L
ALT	P: 5–35 U/L
Albumin	P: 35–50 g/L
Aldosterone	P: 100–500 pmol/L
Alk. phosphatase	P: 30–130 U/L
α-Amylase	P: 0–180 IU/dL
α-Fetoprotein	S: <10 kU/L
Angiotensin II	P: 5–35 pmol/L
ADH	P: 0.9–4.6 pmol/L
AST	P: 5–35 U/L
Bicarbonate	P: 24–30 mmol/L
Bilirubin	P: 3–17 μmol/L
BNP	P: <50 ng/L
CRP	P: <10 mg/L
Calcitonin	P: <0.1 mcg/L
Calcium (ionized)	P: 1.0–1.25 mmol/L
Calcium (total)	P: 2.12–2.60 mmol/L
Chloride	P: 95–105 mmol/L
Cholesterol	P: <5.0 mmol/L
VLDL	P: 0.128–0.645 mmol/L
LDL	P: <2.0 mmol/L
HDL	P: 0.9–1.93 mmol/L
Cortisol AM	P: 450–700 nmol/L
Cortisol Midnight	P: 80–280 nmol/L
CK ♂	P: 25–195 U/L
CK ♀	P: 25–170 U/L
Creatinine	P: 70–100 μmol/L
Ferritin	P: 12–200 mcg/L
Folate	S: 2.1 mcg/L
FSH	P: 2–8 U/L ♂; >25 menopause
GGT ♂	P: 11–51 U/L
GGT ♀	P: 7–33 U/L
Glucose (fasting)	P: 3.5–5.5 mmol/L
Growth hormone	P: <20 mu/L
HbA1C (DCCT)	B: 4–6%
HbA1C (IFCC)	B: 20–42 mmol/mol
Iron ♂	S: 14–31 μmol/L
Iron ♀	S: 11–30 μmol/L
Lactate (venous)	P: 0.6–2.4 mmol/L
Lactate (arterial)	P: 0.6–1.8 mmol/L
LDH	P: 70–250 U/L
LH	P: 3–16 U/L
Magnesium	P: 0.75–1.05 mmol/L
Osmolality	P: 278–305 mosmol/kg
PTH	P: 0.8–8.5 pmol/L
Potassium	P: 3.5–5.3 mmol/L
Prolactin ♂	P: <450 U/L
Prolactin ♀	P: <600 U/L
PSA	P: 0–4 mcg/mL
Protein (total)	P: 60–80 g/L
Red cell folate	B: 0.36–1.44 μmol/L
Renin (erect)	P: 2.8–4.5 pmol/mL/h
Renin (recumbent)	P: 1.1–2.7 pmol/mL/h
Sodium	P: 135–145 mmol/L
TBG	P: 7–17 mg/L
TSH	P: 0.5–4.2 mU/L
T4	P: 70–140 nmol/L
Free T4	P: 9–22 pmol/L
TIBC	S: 54–75 μmol/L
Triglycerides	P: 0.50–2.3 mmol/L
T3	P: 1.2–3.0 nmol/L
Troponin T	P: <0.1 mcg/L
Urate ♂	P: 210–480 μmol/L
Urate ♀	P: 150–390 μmol/L
Urea	P: 2.5–6.7 mmol/L
Vitamin B12	S: 0.13–0.68 nmol/L
Vitamin D	S: 50 nmol/L

Arterial Blood Gases

pH	7.35–7.45
PaCO₂	4.7–6.0 kPa
PaO₂	>10.6 kPa
Base excess	±2 mmol/L

Urine

Cortisol (free)	<280 nmol/24h
Hydroxyindole acetic acid	16–73 μmol/24h
Hydroxymethylmandelic acid	16–48 μmol/24h
Metanephrines	0.03–0.69 μmol/mmol cr.
Osmolality	350–1000 mosmol/kg
17-Oxogenic steroids ♂	28–30 μmol/24h
17-Oxogenic steroids ♀	21–66 μmol/24h
17-Oxosteroids ♂	17–76 μmol/24h
17-Oxosteroids ♀	14–59 μmol/24h
Phosphate (inorganic)	15–50 mmol/24h
Potassium	14–120 mmol/24h
Protein	<150 mg/24h
Protein/creatinine ratio	<3 mg/mmol
Sodium	100–250 mmol/24h

Haematology

WCC	4.0–11.0 ×10⁹/L
RBC ♂	4.5–6.5 ×10¹²/L
RBC ♀	3.9–5.6 ×10¹²/L
Hb ♂	130–180 g/L
Hb ♀	115–160 g/L
PCV ♂	0.4–0.54 L/L
PCV ♀	0.37–0.47 L/L
MCV	76–96 fL
MCH	27–32 pg
MCHC	300–360 g/L
RDW	11.6–14.6%
Neutrophils	2.0–7.5 ×10⁹/L (40–75%)
Lymphocytes	1.0–4.5 ×10⁹/L (20–45%)
Eosinophils	0.04–0.44 ×10⁹/L (1–6%)
Basophils	0–0.10 ×10⁹/L (0–1%)
Monocytes	0.2–0.8 ×10⁹/L (2–10%)
Platelets	150–400 ×10⁹/L
Reticulocytes	0.8–2.0% / 25–100 ×10⁹/L
Prothrombin time	10–14 s
APTT	35–45 s

Paediatric

Pulse Rate (bpm)
Neonate	140–160
Infant <1yr	120–140
1–5 years	110–130
5–12 years	80–120
>12 years	70–100
Respiratory Rate (tachypnoea)
0–2 months	≥60/min
2–12 months	≥50/min
1–5 years	≥40/min
>5 years	≥30/min
Blood Pressure (mmHg)
Term	65/45
1 year	75/50
4 years	85/60
8 years	95/65
10 years	100/70
Weight Formulas
3–12 months	(a + 9)/2 kg
1–6 years	2a + 8 kg
>6 years	(7a − 5)/2 kg
Haemoglobin (g/dL)
Term newborn	13–20
1 month	11–18
2 months	10–15
1–2 years	10–13
>2 years	11–14
MUAC (6 months–5 years)
Obese	>17.5 cm
Normal	13.5–17.4 cm
At risk	12.5–13.4 cm
Moderate malnutrition	11.5–12.4 cm
Severe malnutrition	<11.5 cm
Developmental Milestones
Social smile	1.5 months
Head control	4 months
Sits unsupported	7 months
Crawls	10 months
Stands unsupported	10–12 months
Walks	12–13 months
Talks	18 months
CSF WBC (/mm³)
Term newborn	0–25
>2 weeks	0–5

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