Melanoma

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I- Definition :

Melanoma is a malignant tumor that develops depends on melanocytes (which are dendritic cells at the basal layer of the epidermis and which send their extensions towards the overlying layers, when the subject is dark phototype, they reach even the most superficial layers. In these extensions melanin is stored in melanosomes) Risk factors : phototype clair, sun exposure and the presence of large numbers of nevi

Diagnosis is based on clinical helped by dermoscopy and confirmed by histology and immunohistochemistry

It is a great power metastatic tumor, TRT remains the only curative surgical resection of the importance of early diagnosis and prevention Prognosis depends on theindice Breslow.

II- Epidemiology :

The incidence is increasing : doubles every 10 years for people with white skin, varies depending on the latitude and ethnicity (Australia : 40 new cases / year. Bcp lower among black and yellow)

Age : 30-50 exceptional year in children Slight predominantly female seat :

  • Man : trunk and upper limbs
  • Women : 4 members

Risk factors :

A- Environmental factors : sun exposure :

Sunburns in childhood : intermittent and intense exposures NB : there are rare forms of melanoma that have no relationship with the sun : those palms, soles and mucous membranes (these are very aggressive : affect the dermis vx dissemination)

B- genetic factors :

genetic predisposition : familial 10% (2 on melanoma 3 generations)
genes that predispose : CDKM2A, Larclhri (receptors for MSH)
the phototype : from red to black (surtt 1 and 2)
The phenotype naevique : ability to generate nevi

C- Other :

L’immunodepression : congenital or acquired

DNA repair disorders : le xéroderma pigmentosum (These subjects should not be exposed to the sun)

NB :

  • Most melanomas do not arise from nevi
  • The risk of malignant transformation of small nevus is almost zero, only congenital nevi large have a relatively high risk of degeneration

in summary : sont les FR :

– Familial melanoma ATCDs
– Personal ATCDs
– Phototype clair
– High number of nevi
– Naevus atpiques
– Sun burn

III- The diagnosis :

It is anatomoclinical : clinical suspicion with confirmation anapath

A- Clinique : analyze the morphological appearance of the lesion :
A : asymmetry
B : often irregular edges notched and extending ink flows
C : inhomogeneous color ( light brown, dark, noir, blanc)
D : diameter >6mm or increasing the diameter
E : permanent extension of the lesion with change terrain, diameter, color or shape's review dermoscope : expands the lesion under magnifying glass for a better appreciation

B- Anapath :
Any suspicious lesion should be excised for histopathological examination that allows : melanocytic confirm the nature and appreciate the depth according to Clark Index The evolution of melanoma is biphasic :

  • It spreads horisentalement ribbon above the basement membrane of the epidermis
  • Phase invasive

L'indice Clark :
– Index Clark 1 : epidermis (in-situ) sometimes a bit in the papillary dermis
– Clark 2 : invasion of the papillary dermis
– Clark 3 : papillary dermis interface-reticular
– Clark 4 : reticular dermis
– Clark 5 : hypoderme

L'indice Breslow : measuring the optical microscope on standard histological section of the maximum thickness between the uppermost granular cells and the base of the tumor (the deepest malignant cell) more this index is more great Pc is bad

The forms anapath :

1- Superficial spreading melanoma : SSM
– 60-70% cases
– Macules pigmentée a surface section finement squameuse
– Seat : man : trunk and upper limbs, women : members
– Has several clinical suspicion signs

2- The nodular melanoma :
– 10-20%
– Nodule rounded variable coloring may even be amelanotic with inflammatory halo , it may be a SSM seeping in depth
– Characterized by changing vertical outset fast growing

3- Melanoma acral lentiginous :
– Button ends : palms, plants and angles
– 2-10% in individuals with dark skin type
– brown macula, black or sometimes acromique evolving towards the formation of a plate 2-3 cm (because it goes unnoticed until then )
– The edges are irregular
– The smooth surface or hyperkeratotic (due to the nature of the skin in these areas)
– Nodules or ulcers may appear

NB : Hutchinson's sign : melanoma skin exceeds nail Preferred meta websites : hepatic, lymph node and brain

4- melanoma Freckle :
– 5-10%, touch the face of the elderly
– It is the least aggressive but nodules can penetrate it if no trt
– brown macula type solar lentigo gradually expanding over the years to reach the size of 3-6cm
– The edges are irregular and jagged
– Color : light or dark brown with black Achromic areas

5- melanoma mucosal :

– 5% melanoma, SVT lentigineux
– Rubbish Pc

IV- Differential diagnosis :

  • Le naevus : hyperplasia of melanocytes grouppées (increase)
  • Melanoses circumscribed : increased synthesis of melanin (café au lait spots or freckles redheads topics) so this is the increased functionality * Solar lentigo
  • Seborrheic keratoses : papules brownish or blackish well understood in hummocky surface spread of keratin especially on the back and face
  • The tattooed basal cell carcinoma : dg differential and not clinical anapath
  • Thrombosed angiomas : angioma is a vascular malformation (the strawberry) which can sit anywhere on the body that can thrombose
  • the pyogenic granuloma : Tm is a vascular developed at the expense of capillaries in trauma (surtt ends) during a knife section by esp poor healing papule or nodule angiomatous TRT : electro-coagulation (it may recur). We have to differentiate Tachromique and nodular (recent appearance with notion of trauma) he eventually hyperdermiser * The hemorrhages : posttraumatic (black nail after a hammer by exp)

V- The evolution :

The natural course is marked by local invasion with a possible extension to the adjacent skin or remotely to regional lymph nodes metastasis (soft tissue, foie, brain, the…)

The majority of metastases occur after 2-5 years after TRT Tm primitive

WE- prognosis :

The clinical prognostic factors :

  • male : they leave change
  • Age > 45 years
  • Location : head, cou, mucous

The histological prognostic factors :

  • tumor Thickness : Breslow high
  • Level dermal invasion : Clark high
  • Type nodular and acral
  • Mitotic count per square millimeter high
  • Tumor ulceration : because there is a dermal and vascular disease

VII- Treatment :

1- Surgery :

  • Surgical resection remains the only curative TRT
  • Les limites sont d'Exerese définies by the index of Breslow

2- chemotherapy :

  • Various drugs and protocols are used but melanoma remains insensitive to chemo

3- radiotherapy :

  • Finds use in ganglion damage and metastatic as palliative

4- Biotherapies and anti-tumor vaccination :

promising ways

VIII- Followed :

All 3 month for the 5 first years, then every six months and annually for life This includes a complete clinical examination : cutaneous, mucous, phanariens, examination of lymph node areas, neurological examination, auscultation radiological examinations : each 6 months 1 year or if call signs

IX- Prevention :

  • Primary : Photo by protection and avoidance of sun exposure
  • Secondary : excision of suspicious pigmented lesion
  • Screening : for those at risk : family ATCD, lost…

Dr Benazzouz's course – Faculty of Constantine