MALIGNANT MELANOMA

Outline

• Introduction• Aetiology• Types• Invasion and Metastasis• Risk Factors• Diagnosis and Staging• Treatment and Prevention

Skin:Epidermis - Melanocytes

• Melanocytes:– In stratum basale– Pale “halo” of cytoplasm– Neural crest– Produce melanin and pass it on to

nearby keratinocytes– Melanin covers nuclei of nearby

keratinocytes– Skin colour depends on melanocytes

activity, rather than the number present

MALIGNANT MELANOMA

• A tumour arising from melanocytes of the basal layer of the epidermis

• Less commonly – uveal tract (eye) and meningeal membranes

AETIOLOGY

• The cause is unknown.

• Excessive exposure to sunlight

• Genetic predisposition

RISK FACTORS FOR MELANOMA

• Large numbers of benign naevi

• Clinically atypical naevi

• Severe sunburn

• Early years in a tropical climate

• Family history of MM

Clinical features

• Occur anywhere on the skin– Females (commonest is lower leg)– Males ( back).

• Early melanoma is pain free. The only symptom if present is mild irritation or itch.

AIDS IN CLINICAL DIAGNOSIS

GLASGOW SYSTEM

Major:• Change in size• Irregular pigment• Irregular outline

Minor:• Diameter >6mm• Inflammation• Oozing/bleeding• Itch/altered sensation

AMERICAN ‘ABCDE’ SYSTEM

• Asymmetry

• Border

• Colour

• Diameter

• Examination

Evolving; a mole or skin lesion that looks different from the rest or is changing in size, shape, or color

TYPES OF MELANOMA

• Superficial spreading Malignant melanoma

• Nodular melanoma

• Letingo maligna melanoma

• Acral malanoma

SUPERFICIAL SPREADING

• The most common type of MM in the white-skinned population – 70% of cases

• Commonest sites – lower leg in females and back in males

• In early stages may be small, then growth becomes irregular

NODULAR• Commoner in males

• Trunk is a common site

• Rapidly growing

• Usually thick with a poor prognosis

• Black/brown nodule

• Ulceration and bleeding are common

ACRAL LENTIGINOUS MELANOMA

• In white-skinned population this accounts for 10% of MMs, but is the commonest MM in nonwhite-skinned nations

• Found on palms and soles

• Usually comprises a flat lentiginous area with an invasive nodular component

SUBUNGAL MELANOMA

• Rare

• Often diagnosed late – confusion with benign subungal naevus, paronychial infections, trauma

• Hutchinson’s sign – spillage of pigment onto the surrounding nailfold

LENTIGO MALIGNA MELANOMA

• Occurs as a late development in a lentigo maligna

• Mainly on the face in elderly patients

• May be many years before an invasive nodule develops

DDx

• Superficial spreading melanomas

Benign melanocytic naevi.

• Nodular melanomas

Vascular tumor

Histiocytoma

• Latingo maligna melanoma

Seborrhic keratoses

PROGNOSTIC VARIABLES• The Breslow thickness is

the single most important prognostic variable (distance in mm of the furthest tumour cell from the basal layer of the epidermis)

Breslow depth

5 year survival

In situ 95-100%

<1mm 95-100%

1-2mm 80-96%

2.1-4mm 60-75%

>4mm 50%

• Scalp lesions worse prognosis, then palms and soles, then trunk, then extremeties

• Younger women appear to do better than either men at any stage or women over 50

• Ulceration of the tumour surface is a high risk factor

MANAGEMENT

Surgical resection of tumourMOHS techniqueLymph node dissectionChemotherapyRadiotherapyImmunotherapy

Prevention

• Reduce risk factor exposure:

• Awareness (TV, leaflets, billboards)

• Covering up (sunscreen, sunglasses, clothes)

• Avoidance (less time in sun)

• Screening (possibly feasible)

REFERENCES :

• Clinical Dermatology, Rona M. Mackie

• Dermatology an Illustrated Colour Text, David J. Gawkrodger

• Dermatology, Emedicine