B. Malignant melanoma

Most aggressive malignant tumor of skin, results due to mutations caused by UV radiation. Often seen in light skinned individuals and on sun exposed surfaces. Also seen in oral/ anogenital mucosal surfaces, oesophagus, meninges or uvea.

Warning signs in a pre-existing pigmented lesion include itching, pain, ulceration, increasing size and change in colour or shape.

Melanomas have two phases of growth; i. Radial - horizontal growth and ii. Vertical - downward growth.

ABCDEs of melanoma: Asymmetry, irregular border, variegated colour, increasing diameter, evolution over time, especially if rapid.

Gross:

a. Hyperpigmented lesion on skin

b. Asymmetric, variegated lesions with irregular border

Microscopy:

Malignant Melanoma.png

Malignant cells with brownish black (melanin) pigments invading the dermis and subcutaneous tissue
Tumor cells are spindle to polygonal with pleomorphic nuclei and have moderate cytoplasm
Intracellular and extracellular black to brown (melanin) pigment is seen

Diagnosis

Malignant melanoma

Key Questions & Answers

1. Name pre-malignant lesions of the skin

Actinic Keratosis, Bowen’s disease

2. Name the histological variants of malignant melanoma.

Lentigo maligna, superficial spreading acral/mucosal lentiginous melanoma

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