Medicinus – Cours de Médecine en ligne

Melanoma

Mélanome
(Last Updated On: 10 March 2020)

Introduction:

Epidemiology:

Individual factors:

Atypical nevus syndrome: a particular shape, defined by the presence in large numbers of nevus (50), often of large size (6 mm in diameter), having atypical aspects (irregular edges, polychromy). These subjects will be closely monitored because of the high risk of developing melanoma

Giant congenital Novus: exists at birth, it covers a part of the newborn's body or the entire body of the newborn

Family factor: about 10% of melanomas occur in a "family melanoma" context, defined as at least 2 melanomas over 3 generations, prompting the identification of the familial predisposition gene to melanoma

Environmental factors (solar exposure): The sun is the only environmental factor involved in the epidemiology of melanoma. We can see:

Other factors:

So the risk markers for melanoma:

Positive diagnosis:

ABCDE Rule:

Pruritus or bleeding on contact are also possible when the tumour progresses

A different lesion from the other nevus of the subject (sign of the "naughty duckling") is suspect

Any suspected melanoma lesions must be excised for a histopathological examination

Melanoma Histogenesis: Takes place in a biphasic mode:

Intra-epidermal component: made of melanocytes that form a tablecloth or libraries arranged irregularly along the basal, associated with an invasion of the surface layers of the epidermis by isolated migrating tumour cells and anarchic

Dermal component: invasive, sometimes associated with an inflammatory reaction

The histological examination allows:

The anatomopathological report should specify, for each lesion, a number of parameters that allow:

Breslow Index: it represents the measurement in millimetres, under an optical microscope, of the maximum thickness between the grainy layer of the epidermis at the top and the deepest malignant melanic cell.  Melanomas that do not invade the dermis are not measured and are called "in situ", and there is a quasi-linear correlation between tumor thickness and average survival time

Dermatoscopic examination (epiluminescence): is a non-invasive complementary examination method that uses a semiology of its own, based on the analysis of the image observed as a whole and facilitates differential diagnosis but operator-dependent and be subject to the pitfalls

Anatomopathological classification:

There are 4 major types of melanoma, depending on their clinical and histopathological appearance and their mode of progression

Special clinical forms:

Differential diagnosis:

It should rule out other black tumors that are much more common than melanoma

Seborrheic Keratosis: usually multiple lesions, sitting on the seborrheic areas of the face and trunk, the clinical aspect is that of yellowish, brown or frankly black lesions, with a wart surface and riddled with corks keratosic damage to the skin. Differential diagnosis with melanoma is usually easy, dermatoscopy makes it easy to correct the diagnosis in difficult cases

Tattooed basal cell carcinoma: it can be confusing with an SSM or with nodular melanoma, the beaded appearance of the lesion or the presence of telangiectasies can guide diagnosis, dermatoscopy may also be useful

Histiocytofibroma pigmented: nodular lesions, strictly intradermal, which can be pigmented, the palpation of these lesions which is quite characteristic (undue lozenge) usually helps to correct the diagnosis

Hemangioma: it can take a bluish or black coloration when irritated or thrombosised, dermatoscopy is also characteristic

Botryomycoma: it can pose a diagnostic problem with achromic nodular melanoma, its post-trauma occurrence may help the diagnosis

Subungueal Hematoma: It is generally easy to differentiate from sub-ungueal melanoma.  If there is any doubt, the exeresis must be made in order to have histological confirmation of the exact nature of the lesion

Soft fibrome (molluscum pendulome)

Evolution:

Clinical and histopathological criteria for prognosis (poor prognosis factors)

Treatment:

Surgical: Surgical exeresis must be early, in the non-invasive stage, as it allows healing

Chemotherapy: various drugs and protocols are used but melanoma remains insensitive to chemotherapy

Radiation therapy: is useful in case of lymph node or metastatic disease

Biotherapy and anti-tumor vaccination: appear to be promising pathways

Prevention:

Conclusion:

Exit mobile version