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Pathology - Malignant melanoma
A malignant melanocytic tumor.
Epidemiology • Less prevalent than basal or squamous cell carcinomas of the skin, however far more lethal. • Primarily observed in those with pale skin who have been exposed to sunlight.
Aetiology • Intermittent exposure to high doses of UV radiation constitutes the primary risk factor. • A component of genetic predisposition may also be pertinent. Genetics • Melanomas that develop in areas intermittently exposed to sunlight generally exhibit mutations in BRAF as an initial genetic occurrence. • Progression correlates with the accumulation of mutations in genes such as KIT, MITF, CDKN2A, TP53, and PTEN. • The majority also have chromosomal abnormalities characterized by gains and/or losses of chromosomal segments.
Presentation • The majority of melanomas manifest as pigmented cutaneous lesions exhibiting A symmetry, irregular B ordering, heterogeneous C olour, and D iameter exceeding 6mm (the ‘ABCD’ abbreviation).
Histopathology • A characteristic feature of all types of malignant melanoma is the existence of a neoplastic proliferation of markedly abnormal melanocytes. If the process is restricted to the epidermis, the term melanoma in situ may be utilized. • The term invasive melanoma may be utilized once penetration into the dermis has transpired.
Evolution • The majority of melanomas initially develop as a flat lesion in a radial manner, referred to as the radial growth phase. In this phase, there is either an absence of dermal invasion or the cells within the dermis are incapable of surviving and proliferating. • As advancement occurs, the growth transitions, enabling cells inside the dermis to proliferate. This phase is referred to as the vertical growth phase and is linked to the development of metastatic potential
Prognosis: Survival correlates with the disease stage at the time of diagnosis. • The primary factors determining the stage are the Breslow thickness of the melanoma and the presence of ulceration. • The mitotic rate is also acknowledged as a significant prognostic predictor in vertical growth phase melanomas.
A malignant melanocytic tumor.
Epidemiology • Less prevalent than basal or squamous cell carcinomas of the skin, however far more lethal. • Primarily observed in those with pale skin who have been exposed to sunlight.
Aetiology • Intermittent exposure to high doses of UV radiation constitutes the primary risk factor. • A component of genetic predisposition may also be pertinent. Genetics • Melanomas that develop in areas intermittently exposed to sunlight generally exhibit mutations in BRAF as an initial genetic occurrence. • Progression correlates with the accumulation of mutations in genes such as KIT, MITF, CDKN2A, TP53, and PTEN. • The majority also have chromosomal abnormalities characterized by gains and/or losses of chromosomal segments.
Presentation • The majority of melanomas manifest as pigmented cutaneous lesions exhibiting A symmetry, irregular B ordering, heterogeneous C olour, and D iameter exceeding 6mm (the ‘ABCD’ abbreviation).
Histopathology • A characteristic feature of all types of malignant melanoma is the existence of a neoplastic proliferation of markedly abnormal melanocytes. If the process is restricted to the epidermis, the term melanoma in situ may be utilized. • The term invasive melanoma may be utilized once penetration into the dermis has transpired.
Evolution • The majority of melanomas initially develop as a flat lesion in a radial manner, referred to as the radial growth phase. In this phase, there is either an absence of dermal invasion or the cells within the dermis are incapable of surviving and proliferating. • As advancement occurs, the growth transitions, enabling cells inside the dermis to proliferate. This phase is referred to as the vertical growth phase and is linked to the development of metastatic potential
Prognosis: Survival correlates with the disease stage at the time of diagnosis. • The primary factors determining the stage are the Breslow thickness of the melanoma and the presence of ulceration. • The mitotic rate is also acknowledged as a significant prognostic predictor in vertical growth phase melanomas.
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