Melanoma & Melanocytic Lesions

Question 1

Definition

Answer 1

Malignancy arising from neoplastic transformation of melanocytes, the pigment-forming skin cells. The leading cause of death from skin disease.

Question 2

Aetiology/Risk factors

Answer 2

· DNA damage caused by ultraviolet radiation leads to neoplastic transformation

· 50% arise in existing naevi

· 50% arise in previously normal skin

Question 3

4 histopathological types

Answer 3

o Superficial Spreading (70%)
· Arises in a pre-existing naevus, expands in a radial fashion before a vertical growth phase

o Nodular (15%)
· Arises de novo
· AGGRESSIVE
· NO radial growth phase

o Lentigo Maligna (10%)
· More common in ELDERLY with sun damage
· Large flat lesions
· Progresses slowly
· Usually on the face

o Acral Lentiginous (5%)
· Arise on palms, soles and subungual areas
· Most common type in NON-WHITE populations

Question 4

Epidemiology

Answer 4

· Steadily increasing in incidence

· WHITE races have 20 x increased risk compared to non-whites

Question 5

Presenting symptoms

Answer 5

· Change in size, shape or colour of a pigmented skin lesion
· Redness
· Bleeding
· Crusting
· Ulceration

Question 6

Signs on physical examination

Answer 6

ABCDE criteria for examining moles:

· A - asymmetry
· B - border irregularity
· C - colour variation
· D - diameter > 6 mm
· E - elevation/evolution

Question 7

Benign vs Malignant

Answer 7

Benign

• symmetrical
• even borders
• one colour
• smaller than 6mm
• ordinary mole

Malignant

• asymmetrical
• uneven borders
• two or more colours
• larger than 6mm
• changing in size, shape, colour or another trait

Question 8

Investigations

Answer 8

· Excisional Biopsy - histological diagnosis and determination of Clark’s Levels and Breslow Thickness (two methods of determining the depth of penetration of a melanoma)

· Lymphoscintigraphy - a radioactive compound is injected into the lesion and images are taken over 30 mins to trace the lymph drainage and identify the sentinel nodes

· Sentinel Lymph Node Biopsy - check for metastatic involvement

· Staging - using ultrasound, CT or MRI, CXR

· Bloods - LFTs (because the liver is a common site of metastasis)