What is Nodular melanoma

Prevalence: accounts for about 10-15% of all cases of melanoma.

Incidence: more frequent in males than females, with a ratio of 2:1. Nodular melanomas occur most often in the fifth or sixth decade.

Site: Nodular melanomas affect any area of skin, but are more often found on the extremities.

Course: Nodular melanoma lesions appear and evolve over months and tend to extend vertically in the skin.

Appearance: Nodular melanoma is most commonly dark brown, red-brown, or red-black and is dome-shaped, polypoid, or pedunculated. It is occasionally amelanotic or flesh colored and resembles flesh-colored dermal nevi or basal cell carcinoma. These amelanotic melanomas represent 2% of all melanomas. Lesions eventually erode, ulcerate and bleed.

Differential diagnosis: Hemangioma which is compressible with its color density changed with firm finger pressure.

What is Superficial Spreading Melanoma

Prevalence: the most common subtype of melanoma, accounting for 70-80% of all cases.

Incidence: most common in middle age, from the fourth to fifth decade, slightly more common in females than males and usually affects Caucasians.

Anatomic site: Any area of the skin may be affected but they are most often found on the upper back of both men and women and on the legs of women.

Clinical appearance: Superficial Spreading Melanoma lesions tend to be greater than 6 mm in diameter, flat and asymmetric with varying colors.

Specific features: The hallmark of Superficial Spreading Melanoma is the haphazard combination of many colors, but it may be uniformly brown or black. Colors may become more diverse as time proceeds. A dull red color is frequently observed, which may occupy a small area or may dominate the lesion.

Course: Superficial Spreading Melanoma begins in a pre-existing lesion, in a nonspecific manner and then changes shape by radial spread and regression.
The radial growth phase (lateral spread of lesions within the skin): may last for months or for years, before nodules develop. The random migration of cells, along with the process of regression, results in lesions with an endless variety of shapes and sizes. The shape is bizarre if left untreated for years.

What are Atypical Nevi

Onset: begin to appear during early childhood. The characteristic features of atypical moles are present at the time of puberty. Unlike common acquired melanocytic nevi, which stop appearing after age 30, atypical nevi continue to appear well into adulthood.
Size: ranging from 6 mm-15 mm in diameter.
Border: irregularly outlined, indistinct, and fades imperceptibly into the surrounding skin.
Color: variegated with a haphazard mixture of pink, tan, brown, and black.
Surface: irregular, often with a central or eccentric papule surrounded by a prominent macular component.
Site: anywhere in the skin but occur most commonly on the trunk and upper extremities. Affected persons often have nevi in sun-protected areas, such as the scalp, groin, buttocks, the breasts in women, and the palms and soles.
Progression: increased risk of melanoma, most often the superficial spreading type.