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Definition: highly malignant tumour which usually pigmented but may be without pigmentation ( amelanotic melanoma).
Incidence: 2/10,0.00 of population. i.e. rare disease whis is very rare in children, negros and Asians. Shows higher incidence in Australians.
Common Sites: Any where in the skin but common in: - Nail fold. - Mucous membranes of the nose & lips. - Anal canal. - Sole of the foot "Common site in Egypt". - Iris of the eye is rare site of lry malig. melanoma. Precancerous lesions:-
I- Benign melanoma criteria of turning it into malignant:
1- Rapid growth. 2- Falling of hairs.
3- Become painful or itchy. 4 Become ulcerated or indurated.
5- Enlarged draining L.N.
II- Start de novo i.e malignant from the start.
Pathology:
- All malignant melanomas arises from melanocytes in the dermo - epidermal junction.
There are four parameters of histological grading:
1- High mitosis.
2- Ulceration.
3- Clark's levels of invasion.
4- Breslow's depth of invasion. The thickness is measured by an optical micrometer from grannular layer to the deepest melanoma cells in the dermis. Lesions less than 0.67mm in thickness have a very favourable prognosis.
- Clark's levels of invasion provide a helpful method of grading malignant melanomas.
< Level I: Malignant cells not infiltrate basement membrane.
< Level II: Infiltrate B.M. but not fill papillary layer of the dermis.
< Level III: Fill the papillary layer of the dermis.
< Level IV: Reach the reticular layer of the dermis.
< Level V: Infiltrate S.C. Fat. Spread:
- Rapid by both Lymphatic & blood spread Mainly to liver.
- Sometimes amelanotic melanoma gives melanotic 2ries.
Clinical Picture:
I- At the site of the lesion. Five clinical types are noticed:-
a- Lentigo maligna. b- Superficial Spreading type.
c-Nodular melanoma. d- Acral lentigenous (in the palm and sole).
e- Amelanotic melanoma.
II- Melanuria may occur in cases with extensive metastasis. "The urine become dark when exposed to air".
Treatment:
I- Surgery: It is highly radio resistant so, surgery is the main line of treatment.
1- Biopsy to detect level of the melanoma.
2- Excision with 5cm safety in all direction with underlying deep fascia.
3- Draining L.N.
ط If enlarged do block dissection
ط Some prefer to delay block dissection for 3 weeks to act as filter.
II- Chemotherapy: Melphalan & Actinomycin D. Best results are obtained by isolated regional perfusion. By this way you can give doses which can not be given systematically.
III- Immunotherapy:
Some tumours regress spontaneously so, vaccination with B.C.G. or small pox vaccine may immunity with regression of the melanoma.
SOURCE: Prof. AYMAN SALEM'S BOOK
Copyright: (Vascular Society of Egypt ) & (Medical Educational web)
Not to be reproduced without permission of Vascular Society of Egypt
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