Skin cancer facts: Malignant Melanoma

Skin cancer ---> Melanoma skin cancer

Skin Cancers are the most commonly diagnosed malignant tumors in the United States, with an incidence of approximately 1.4 million new cases annually. Basal cell and squamous cell skin carcinoma account for 96% of new non melanoma skin cancers. Malignant Melanoma accounts for 4% of skin cancers.

Risk factors for development of skin melanoma include ultraviolet light (UVL) exposure, fair complexion/inability to tan, blue or green eyes, blonde or red hair, freckling, history of actinic keratosis or non melanoma skin cancer, history of blistering or peeling sunburns, immunosuppression, personal or family history of melanoma, CDKN2A/p16/MC1R mutation, xeroderma pigmentosa, atypical (dysplastic) nevus, more than 100 normal nevi, and giant congenital melanocytic nevus.

The ABCD rule is used to assess skin lesions for melanoma risk: A is for asymmetry; B is border irregularity; C is color, and D is diameter greater than 6 mm.

Melanoma prognosis is inverse correlated to tumor thickness; ulceration and increased mitotic rate are independent survival risk factors; nodal tumor burden (uninvoled versus microscopic versus macroscopic disease) has an inverse correlation with survival.

Treatment: For melanoma in situ, excision margins of 0.5 to 1 cm are indicated; for invasive melanoma, wide excision of the primary tumor with margins generally ranging from 1 to 2 cm is indicated for local control.

Clinically involved lymph nodes should be resected; patients with primary melanomas of 1 mm thickness or greater and clinically negative nodes should be considered for sentinal lymph node biopsy.

Malignant melanoma

Skin cancer ---> Melanoma skin cancer

Melanoma arises from malignant proliferation of melanocytes.
Epidemiology
The incidence of and mortality from melanoma are increasing. Its incidence is approximately 10 per 100 000 per year. The highest incidence occurs in white-skinned individuals in Australia and New Zealand. Melanoma is more common in women than in men.
Pathology
Ultraviolet exposure is a major etiological factor, particularly short, intense exposure resulting in sunburn during childhood. Phenotypic factors associated with melanoma include fair skin, red or blonde hair, blue eyes, inability to tan, freckles, lentigines, large numbers of benign melanocytic nevi and the presence of dysplastic nevi.
Important risk factors for malignant melanoma
Presence of precursor lesions (dysplastic melanocytic nevi)
Family history of melanoma in parents or siblings
Skin phototypes I and II with an inability to tan
Excess sun exposure, especially during childhood
Clinical features
Malignant melanoma has two patterns of growth, radial and vertical. Radial growth is horizontal within the epidermis and superficial dermal layers, as in the lentigo maligna, acral/mucosal lentiginous and superficial spreading types. During this stage of growth the tumor does not have the capacity to metastasize. Vertical growth occurs with time, and the melanoma grows downwards into the deeper dermal layers as an expansile mass, lacking cellular maturation. This correlates with the emergence of a clone of cells with metastatic potential. The nature and extent of this vertical growth phase determine the biological behavior of malignant melanoma. The different types of malignant melanoma are categorized on morphology and histological findings.
Superficial spreading
Superficial spreading is the most common variant of melanoma (70%), presenting as a macule or papule, usually greater than 0.5 cm in diameter. There is variable pigmentation (from pale brown to blue-black), an irregular edge, and surface oozing or crusting. In males it most frequently presents on the back, while in females the leg is the most common site. In the radial growth phase it is characterized by atypical melanocytes, singly and in clusters, widely scattered throughout the layers of the epidermis. Left untreated it may progress to the vertical growth phase over months to years.
Nodular melanoma
Nodular melanoma is the second most common variant (14%) and, by definition, presents in the vertical growth phase. It classically presents as a rapidly enlarging, frequently ulcerated, blue-black nodule.
Lentigo maligna
Lentigo maligna presents as an irregularly pigmented macule, slowly enlarging over many years, commonly on the cheek or temple of an elderly person. It is characterized by basally located atypical melanocytes. Development of a more rapidly growing, deeply pigmented papule or nodule indicates dermal invasion by malignant melanocytes (lentigo maligna melanoma).
Acral lentiginous melanoma
Acral lentiginous melanoma is an uncommon subtype, although it is the predominant variant in the Afro-Caribbean population. The sole of the foot is most often affected and lesions may also arise on the digits. Subungual or periungual melanoma, a variant of acral lentiginous melanoma, occurs either as a linear pigmented streak in the nail or an isolated nail dystrophy, accompanied by the pigmentation of the proximal nail fold (Hutchinson's sign).
Amelanotic melanoma
Amelanotic melanoma is a non-pigmented variant of melanoma.
Malignant melanoma on mucous membranes
Malignant melanoma on mucous membranes is very rare and may affect the vulva, urethra and anus. It has a poor prognosis, due in part to its often advanced stage at presentation.
Investigations
Skin biopsy
An excision skin biopsy must be performed to confirm the diagnosis. This will give important histological data and provide valuable staging information.
Management
The management of malignant melanoma varies according to the stage at presentation, and ranges from surgical excision to radiotherapy and chemotherapy.
Prognosis
Melanoma has a mortality rate of 25% and therefore early diagnosis and treatment is essential. Prognostic factors include thickness, level of invasion, gender and site of tumor.
Histological data from melanoma
Clarke's level
I melanoma cells confined to epidermis
II melanoma cells invade papillary dermis
III melanoma cells completely occupy papillary dermis
IV melanoma cells invade mid-reticular dermis
V melanoma cells invade subcutaneous fat

Tumor thickness in mm from granular layer of the epidermis to maximum depth (Breslow thickness)
Presence of radial or vertical growth
Tumor infiltrating lymphocytes
Mitoses per mm2
Presence or absence of tumor regression (mitosis, inflammatory infiltrate, pigmentary incontinence, fibrosis and dermal scarring, and vascular proliferation)
Microsatellites
Evidence of perineural infiltrate
Evidence of vascular and lymphatic invasion
Whether excision is complete

TNM staging system for melanoma
Stage (T) Primary tumor Lymph node (N) Distant metastases (M)
0 In situ tumors No nodes No Distant metastases (M)
IA -1mm, IIB 2.01-4 mm with ulceration No nodes No Distant metastases (M)
>4 mm, no ulceration No nodes No Distant metastases (M)
IIC >4 mm with ulceration No nodes No Distant metastases (M)
IIIA Any Breslow thickness, no ulceration Micrometastases in nodes No Distant metastases (M)
IIIB Any Breslow thickness with ulceration Micrometastases in nodes No Distant metastases (M)
Any Breslow thickness, no ulceration Up to 3 palpable nodes No Distant metastases (M)
Any Breslow thickness ± ulceration No nodes but in-transit metastases or satellites None
IIIC Any Breslow thickness with ulceration Up to 3 palpable nodes No Distant metastases (M)
Any Breslow thickness ± ulceration 4 or more palpable nodes or matted nodes or in-transit metastases with nodes No Distant metastases (M)
IV M1: skin, subcutaneous or distant lymph nodes
M2: lung
M3: all other sites or any site with raised lactate dehydrogenase

Skin Mole or Nevus

Melanoma skin cancer ---> Pre skin cancer ---> skin cancer moles

Lentigo
A lentigo is a common lesion that presents as a small, pigmented macule due to an increase in the number of melanocytes within the basal layer of the epidermis. These are unaffected by sunlight. Solar lentigines develop on sun-exposed sites following either acute severe sunburn in young adults or chronic ultraviolet exposure in the elderly. Multiple lentigines may rarely be a manifestation of Peutz-Jeghers syndrome, particularly when distributed on the lips, buccal mucosa and acral sites.

Acquired melanocytic nevi
Acquired melanocytic nevi are common benign proliferations of melanocytes. They can be classified according to the site of the cluster of melanocytes. Junctional nevi describe the position of the cells at the dermal-epidermal junction above the basement membrane. Intradermal nevi describe cells that are exclusively in the dermis. Compound nevi have histological features of both junctional and intradermal nevi.
Junctional nevi present as small, dark brown, evenly pigmented, symmetrical macules. The majority of naevi in children are junctional and occur on any body site. Compound nevi (where melanocytes are present in both the epidermis and dermis) occur at any site and vary from light brown papules to dark brown papillomatous plaques. Intradermal nevi are usually detected in the third decade, frequently on the face, and may be devoid of pigment. They may be dome-shaped or pedunculated skin tags. These lesions appear in early childhood and reach a maximum in young adulthood. There is then a gradual involution, and most lesions disappear by the age of 60. A skin biopsy is only required when clinical differentiation from malignant melanoma is difficult.

Blue nevus
A blue nevus is an acquired, benign, firm, dark blue to black, sharply defined papule representing a deep dermal aggregate of melanocytes. The dermal melanocytes are thought to represent melanocytes which have failed to migrate from the neural crest to the epidermis during fetal life. Blue nevus is most common on the dorsum of hands or feet of older children and young adults. Malignant change is very rare.

Spitz nevus
A Spitz nevus is a benign melanocytic tumor that is distinct from acquired melanocytic nevi on both clinical and pathological grounds. The majority occur in children as a discrete, red-brown or pink papule on the face. The clinical presentation is distinctive and there is often a history of recent rapid growth. Differentiation from malignant melanoma may be difficult and in these cases complete excision is recommended.

Mongolian spot
A Mongolian spot is a congenital grey-blue macular lesion that can occur anywhere on the skin but is characteristically located on the lumbo-sacral area. Histologically there are ectopic melanocytes in the dermis, possibly interrupted in their migration from the neural crest to the epidermis. Mongolian spots disappear in early childhood. No melanomas have been reported in these lesions.

Nevus spilus
A nevus spilus is a common lesion consisting of a light brown macule, varying in size from a few centimeters to a very large area, with many darker small macules (2-3 mm) or papules scattered throughout. Histologically, the background macule shows an increased number of melanocytes and the scattered lesions are either junctional or compound nevi. Malignant melanoma very rarely arises in these lesions.

Dysplastic melanocytic nevus
Dysplastic melanocytic nevi are melanocytic lesions with atypical clinical and histological features. They are regarded as potential precursors of superficial spreading melanoma and also as markers of persons at risk for developing primary malignant melanoma. These pigmented lesions are clinically distinct from acquired melanocytic nevi, being larger and more variegated in color, with an asymmetrical outline and irregular border. Lesions may occur sporadically or may arise against a background of dysplastic nevus syndrome, an autosomal dominant condition with multiple atypical nevi. Surgical excision of lesions with minimal margins is recommended, especially in lesions that are changing or those that cannot be closely followed by the patient (on the scalp or back).

CLINICAL ALERT
Six signs of malignant melanoma
A
Asymmetry in shape
B
Border is irregular
C
Color variation-shades of brown, black, grey, red and white
D
Diameter is usually large, >6 mm
E
Elevation is almost always present

Malignant Melanoma pictures

skin cancer pictures ---> melanoma skin cancer ---> melanoma pictures.

Causes of Melanoma

Melanoma skin cancer ---> Causes of melanoma

Numerous environmental and genetic risk factors have been implicated in the development of cutaneous melanoma. Risk factors include ultraviolet light (UVL) exposure, fair complexion/inability to tan, blue or green eyes, blonde or red hair, freckling, history of actinic keratosis or nonmelanoma skin cancer, history of blistering or peeling sunburns, immunosuppression, personal or family history of melanoma, xeroderma pigmentosa, atypical (dysplastic) nevus, more than 100 normal nevi, and giant congenital melanocytic nevus. Patients with a significant history of sun exposure are at particularly high risk, especially if they experienced peeling or blistering sunburns, even during childhood. Melanoma occurs infrequently in skin of color, suggesting that skin pigment plays a protective role. Melanoma incidence is subject to large geographic and ethnic variations, mainly because of an inverse correlation with latitude and with degree of skin pigmentation. Populations residing closer to the equator have a higher incidence of melanoma. Certainly UVL exposure from sun or artificial light sources is considered the best-known risk factor. However, UVL exposure does not cause all or even most melanomas.
Adults with more than 100 clinically normal-appearing nevi, children with more than 50 clinically normal-appearing nevi, and any patient with atypical or dysplastic nevi are at risk. A prior history of melanoma places a patient at increased risk, with 5% to 10% of individuals developing a second primary melanoma. This risk of developing a second primary is lifelong and can occur anywhere on the skin. Therefore, long-term surveillance with a thorough total body examination is recommended.
A genetic component has been implicated in the pathogenesis of melanoma. Of patients with melanoma, 10% to 15% report a positive family history. The genetic etiology of melanoma represents an area of future discovery.
The hereditary nature of cutaneous melanoma was also noted in the 1970s. Members afflicted with the B-K mole syndrome, named after two families, acquired large, irregular, and dysplastic nevi, often in sun-protected regions of the body such as the scalp and trunk. Familial association of melanoma among individuals with atypical nevi, is termed Familial Atypical Multiple Mole-Melanoma Syndrome, or FAMMM syndrome, with an autosomal dominant inheritance pattern. An atypical nevus is not a pre melanoma but represents a genetic marker for increased risk of development of melanoma, which may occur anywhere on the skin surface including sun-protected sites. In fact more than 50% to 75% of melanomas develop on clinically normal skin de novo, not in preexisting melanocytic lesions.
Xeroderma pigmentosa (XP) is a rare autosomal recessive disorder associated with a reduced or absent ability to repair DNA damaged by ultraviolet light. Consequently, this disorder results in the development of multiple primary cutaneous malignancies, including melanoma as well as BCC and SCC. Individuals are usually diagnosed with their first cancer before the age of 10 years. Unfortunately, the development of skin cancers is relentless.
Congenital melanocytic nevi (CMN) are present at birth or appear within the first 6 months of infancy. An estimated 1% to 6% of children are born with CMN. The nevi are classified by size. Small CMN measure less than 1.5 cm in diameter and account for the majority of lesions. Medium CMN measure between 1.5 and 19.9 cm in diameter. Large CMN, also termed giant congenital nevi, measure 20 cm or greater. This large size can lead to significant cosmetic and psychosocial implications. The risk of melanoma development in small and medium-size CMN is similar to any other area of skin. Melanoma development in small and medium CMN usually occurs after childhood and arises from the dermoepidermal junction, making early detection feasible. Routine prophylactic removal of small and medium CMN is rarely indicated in the absence of signs or symptoms for malignant progression. Conversely, giant congenital nevi carry an increased risk for melanoma, with an estimated rate of 5% to 20%. Of giant congenital nevi that progress to melanoma, 70% are diagnosed prior to age 10 years. Melanoma can originate deep in the epidermis in giant congenital nevi. Consequently, diagnosis within the setting of giant congenital nevi is challenging and may develop deep in the skin with a more advanced primary lesion.