What Is Melanoma?

 

I. Definition

Melanoma is a malignant tumor that develops from melanocytes( the cells that produce melanin).

II. Epidemiology

Melanoma often occurs at the age between 50 to 60. It is rare for children before reaching puberty. It mostly affects white people more than black and Asian people.
Ultraviolet light (UV) is one of the factors that can contribute to the disease. Around 10% of melanoma are developed from a family that we call ‘familial melanoma‘.There are so many genes that are considered as the main factors, but the most risk genes are CDKN2A, mutation of the tumor suppressor genes observed in 10% to 30% of familial forms.

III.Risk factors

-Familial melanoma background
-Light skin and hair
-Have a lot of nevi
-Have a history of burned skin or staying too long under the sunlight

IV. Diagnosis

-Basically, we diagnose the melanoma by inspection(appearance) or we can use dermoscopy. The positive diagnostic is confirmed by anatomy pathology examination that can give the patients the right decision for treatment and prognostic.
-We have some rules ( ABCDE )to recognize melanoma. Melanoma is the lesion of melanocyte, pigment around 80 to 90% of cases.

A stands for asymmetry

B stands for borders irregularity

C stands for color (brown,black or blue,depigmented,halo, inflammation)

D stands for diametre > 6 mm

E stands for evolution (size,form,color,resolution)

-Pruritus and bleeding when touching also occurs. All the lesions with a suspicion of melanoma must be excised for a histopathology examination.
-The diagnosis of melanoma is histology. Histology permits:
=>Identify the nature of melanocyte of the tumor
=>Confirm the malignant of the tumor :
=>Confirm the complete character of exeresis
-There are 2 phases of the evolution of melanoma.
1/.Melanomas with a horizontal extension phase
Superficial Spreading Melanoma (SSM) with increased horizontal intraepidermal then vertical

SSM : superficial spreading melanoma

Melanoma of Dubreuilh (10% of cases). It is situated at the zone exposed to the light and especially on the face of the old people(60 years old) and then it progresses to horizontal during months or years

Melanoma of Dubreuilh

Acral lentiginous melanoma(ALM)(2 to 5% of cases). It is located at the palms, the toes, the lateral borders of fingers and ears, and under the nails.
Melanoma of buccal mucosa et genitals.
2/.Melanoma without horizontal extension phase
Nodule melanoma (10 to 20% of cases), progress to the vertical invasive pattern.

V. Differential diagnosis

–Seborrheic keratosis: frequently after 40 to 50 years old: border nets, small white grains, and nonpalpable surface.
-Basal carcinoma pigmented: translucid aspect or telangiectasia.

seborrheic keratosis

-Histiocytofibrome dermatofibroma: indurated pastille

Histiocytofibrome dermatofibroma

–Thrombosed angioma is similar to small nodule melanoma

Thrombosed angioma

VI. Evolution

+Primitif melanoma can progress :
=>Local recurrence at the initial tumor
=>Cutaneous metastases or subcutaneous between the tumor and the first site of ganglions.
=>Metastases of regional ganglions
=>Visceral metastases (any organs)

VII.Clinical findings and histology

A. Melanoma primary tumor, stade I et II
-The prognostic factor is histology :
=>The thickness of the tumor or Breslow’s depth still the principal characteristic in practice. Ulceration can be the important point that we can know about the profound.
mitotic index (number of mitoses/mm2)has a value of prognosis independent for any tumors that less than 1 mm
-The poor prognosis of clinical findings are :
=>Sex: male
=>Advanced age
=>Certains locations: body, head, and neck
B. Melanoma in stade local adenopathy( N: stadeIII)
-Principal prognostic factors are :
=>Number of metastases ganglions
=>Presence of ulceration
C. Melanoma in stade metastases to distance area (M: stade IV )
In this stade, the patients are resistant to chemotherapy so they can survive for 9 months.
BRAF inhibitor(v-RAF murine sarcoma viral oncogene homolog B1) and MEK inhibitor (Methyl ethyl ketone)are used for melanoma with a mutation in BRAF V600(45% of cases)

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