MALIGNANT MELANOMA

<|> Malignant melanoma -

Malignant melanoma is one of the most rapidly spreading cancer of the skin. It is rare before puberty.The tumor spreads locally as well as to distant sites via lymph to the regional lymph nodes and via blood to distant sites like lung, liver, brain, spinal cord and adrenals.

Predisposing conditions :
1. Exposure of skin to excessive sunlight
2. Persistent change in appearance of a mole.
3. Presence of pre-existing naevus, especially dysplastic naevus.
4. Family history of melanoma.
5. Higher age of patient.
6. More than 50 moles of 2 mm or more diameter.

Common locations :

Skin, oral and ano-genital mucosa, esophagus, conjunctiva, orbit, leptomeninges.

General appearance :

1. Flat or slightly elevated asymmetric naevus with variegated pigmentation, irregular border, diameter more than 6 mm.

2. It has recently undergone colour changes, ulceration, bleeding and increased in size.

Types of malignant melanoma : Depending on clinical course and prognosis they are of 4 types -

1. Lentigo maligna melanoma - good prognosis.

2. Superficial spreading melanoma - prognosis is worse than the previous one.

3. Acral lentigenous melanoma - occurs more commonly on sole, palm and mucosal surface, prognosis is worse than the previous one.

4. Nodular melanoma - worst prognosis.

Microscopic appearance :

1. Marked junctional activity at the dermo-epidermal junction and tumor cells grow downward into the dermis.

2. Epitheloid or spindle-shaped tumor cells with amphophilic cytoplasm, large pleomorphic nuclei with conspicuous nucleoli.

3. Mitotic figures are often present.

4. Multi-nucleated giant cells may occur.

5. Melanin pigment, if present, tends to be in the form of uniform fine granules.

6. Some amount of inflammatory infiltrate may be present.

Prognosis :

Prognosis depends on the depth of invasion of the tumor in the dermis.