Armando Hasudungan
Biology and Medicine videos

Melanoma

Overview

Video: Melanoma Overview

 

Overview

Overview Melanoma accounts for 4 percent of all dermatological cancer. Melanoma has the highest mortality rate of all dermatological cancers, only 14 percent of patients with metastatic melanoma survive for five years. Melanoma is one of the most common cancers in young adults.

Overview

Overview Melanoma accounts for 4 percent of all dermatological cancer. Melanoma can look like a pigmented lesion, usually asymmetrical in appearance with irregular borders. There can be bleeding and ulcerating as well.

Anatomy and Physiology

The skin consist of three layers, from superficial to deep:

  • Epidermis
  • Dermis
    • Papillary layer
    • Reticular layer
  • Hypodermis (some don’t classify it as skin)

The epidermal layer are made up mainly of keratinocytes, which are squamous epithelial cells high in keratin (protein). Other cells residing in the epidermis include:

  • Melanocytes – produce melanin
  • Langerhan cells – immune cell, basically a dendritic cell of the skin
  • Merkel Cells – tactile cells for sensation

Melanocytes are mature melanin-forming cells found in many parts of the body (eye, ear, hair, heart, bone), but especially in the skin. Through a process called melanogenesis, these cells produce melanin, which is a pigment found in the skin, eye and hair. Vitamin D and UV light stimulate melanocytes to produce melanin.

 

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Watch Dermatology Introduction

Risk Factors

Riskfactors

 

Signs and Symptoms

  • Atypical naevi
  • Ulceration and bleeding
  • Constitutional symptoms

Examination – ABCDE

  • A – asymmetry
  • B – borders (irregular and/or distinct)
  • C – colour (varied)
  • D – Diameter (increasing or >6mm)
  • E – Elevation and Evolution (most important as in changing rapidly/growing)
Remember Blanching. Press down on the lesion for ~3 seconds. Release if pale and refills there is a vascularity involved.

Diagnosis

  • Examination ABCDE
  • If Melanoma suspected perform a skin biopsy
  • Breslow’s thickness can be used to stage Melanoma and establish prognosis

Differential Diagnosis

  • Seborrhoeic keratosis
  • Pigmented basal cell carcinoma
  • Actinic keratosis
  • Benign melanocytic naevi
  • Spitz naevus
  • Haemangioma
Think Squamous cell carcinoma is not a good differential because it is not pigmented

Investigations

  • Dermatoscope
  • Skin Biopsy
  • Chest X-ray for metastasis
Remember 1.4cm depth is dangerous

Pathophysiology

  • Melanoma arises from melanocytes
  • Genetics and environmental factors play a role in the pathogenesis
  • A proportion of melanoma arise from pre existing naevi

Pathophysiology

Mutated BRAF and NRAS genes are most common in superficial spreading and nodular melanoma.

Pathology

Different types of Melanoma

  • Superficial spreading (most common)
  • Nodular (most dangerous)
  • Lentigo maligna
  • Acral lentiginous

Pathology

 

P

Pathological Differences between Benign and Malignant tumours
Malignant Benign
Invasive Non-Invasive
Poorly differentiated Well Differentiated
High mitotic rate Normal mitotic rate
Non-capsulated Capsulated
Usually large growth Usually small growth
Not well circumscribed Well circumscribed

Staging

Clark’s Staging – Important histologically
Clark’s Level Histological characteristic
I Confined to the epidermis “in situ”
II Invasion of the papillary dermis
III Filling of the papillary dermis
IV Invasion of the reticular dermis
V Invasion of the deep, subcutaneous tissue
Breslow’s Staging – Important Prognostically
Breslow’s Thickness Depth of tumour invasion
I ≤0.75mm
II 0.75-1.5mm
III 1.51-2.25mm
IV 2.26-3.0mm
V >3.0mm

Management

  • Surgical excision
  • Topical Imiquimod
  • Surgical excision +/- sentinel lymph node biopsy

Complications and Prognosis

Complication

Metastasis

Treatment adverse effects

  • Chemotherapy
  • Radiotherapy
  • Immunotherapy (causes flu-like symptoms)

Prognosis The most important prognostic indicators are Breslow’s depth of the tumour and lymph node status.

  • Stage 0 (in-situ melanoma): >98%
  • Stage I (Breslow’s depth <1 mm and no nodal or metastatic disease): 90% to 95%
  • Stage II (localised disease, intermediate to thick depth): 45% to 78% (78% for non-ulcerated melanoma of depth 1 to 4 mm; 45% for an ulcerated melanoma >4 mm depth)
  • Stage III (nodal metastases): 69% (non-ulcerated melanoma of any depth with a single positive node) to 26% (ulcerated melanoma of any depth with 4 or more positive nodes)
  • Stage IV (metastatic): overall prognosis is bleak; 3% to 10% depending on the extent and sites of metastasis.

Prevention

Preventative

References

UpToDate
RACGP
Best Practice