Melanoma and Melanocytic Lesions

Question 1

Define melanoma

Answer 1

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

Question 2

What are the causes/risk factors of melanoma?

Answer 2

• DNA damage caused by ultraviolet radiation leads to neoplastic transformation
• 50% arise in existing naevi
• 50% arise in previously normal skin

FOUR histopathological types
• Superficial Spreading (70%)
- Arises in a pre-existing naevus, expands in a radial fashion before a vertical growth phase
• Nodular (15%)
- Arises de novo
- AGGRESSIVE
- NO radial growth phase
• Lentigo Maligna (10%)
- More common in ELDERLY with sun damage
- Large flat lesions
- Progresses slowly
- Usually on the face
• Acral Lentiginous (5%)
- Arise on palms, soles and subungual areas
- Most common type in NON-WHITE populations

Question 3

What are the symptoms of melanoma?

Answer 3

• change in size, shape or colour of a pigmented skin lesion
• redness
• bleeding
• crusting
• ulceration

Question 4

What are the signs of melanoma?

Answer 4

malignant:
• asymmetry
• border irregularity
• colour variation
• diameter >6mm
• elevation/evolution

Question 5

What investigations are carried out for melanoma?

Answer 5

• excisional biopsy
• 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
• staging
• LFTs - liver is a common site of metastasis