Melanoma Types
There are several melanoma types, each with distinctive signs and symptoms. The most common melanoma type is superficial spreading melanoma (SSM), accounting for 70 percent of all diagnosed melanoma skin cancer cases in the United States. SSM is characterized by flat and irregular shaped lesions, which are varying shades of black, brown, gray, blue, pink or white. Found mostly in Caucasians, this melanoma type can develop at any age and in any location on the body, especially on the legs of females and between the neck and pelvis of males. The first indication of SSM is an elongated freckle that seems to spread sideways on the skin. The lesion progresses rapidly – spreading outward, getting darker in color and becoming increasingly inflamed.
The second melanoma type is nodular melanoma (NM). It is the most aggressive type of melanoma, accounting for 15 percent of all cases in the United States. The principal symptom found with NM is a dark blackish-blue or bluish-red raised area, although it may be amelanotic or colorless. The lesion grows deep into the skin faster than it spreads outward, and often forms in a spot that did not previously have a mole or lesion. For this reason, NM often goes undetected until it is too late. This melanoma type can develop at any age, but is most common in people over the age of 60. Males are more prone to developing nodular melanoma.
Lentigo maligna melanoma (LMM) is confined to the top most layer of skin and is generally found on the face, neck and arms of elderly individuals due to sun damage. It accounts for ten percent of all melanoma skin cancer deaths in the United States. Sometimes called "Hutchinson's freckle," LMM looks like a large, flat, tan stain on the skin. With this malignant melanoma type, the progression is extremely slow, sometimes taking ten to fifteen years before it becomes irregular in shape or color. At this stage, the lesion can be mistaken for lentigo simplex, a non-cancerous blemish often referred to as a "sun spot" or "age spot." After becoming irregular, the lesion can progress very rapidly and develop into a deep, darkly-colored nodule.
Acral lentiginous melanoma (ALM) is a less common type of melanoma skin cancer, only making up five percent of American cases; yet, this melanoma type accounts for 50 percent of the cases found in Asians and dark-skinned individuals. ALM is often referred to as a "hidden melanoma" because the discrete tumors develop in places that most would not think to examine – palms, soles of feet, scalp, genitals and between toes. The tumor becomes more irregular in shape and color as it increases in size. Often times the tumor will dig deep into multiple skin layers, yet the surface will remain undisturbed. Acral lentiginous melanoma type is found most often in African Americans.
Acral lentiginous melanoma can be further divided into subtypes. Subungual melanoma is often found under finger or toe nails, specifically the thumb and big toe. A slight discoloration is the first symptom, but because of the location and common incidence in dark-skinned individuals, it is often overlooked. Mucosal melanoma develops in the mucosal tissue of the mouth, nose, esophagus, anus, urinary tract and vagina. The symptoms are similar to other infections – itching and bleeding – thus this type of melanoma skin cancer is sometimes neglected or misdiagnosed. Although rare, there are three types of melanoma skin cancer found in the eye: ocular, conjunctiva and choroids. These melanoma types are linked to chronic sun exposure without proper eye protection. Ocular melanoma is found in the pigment-containing cells of the retina. It rarely produces any symptoms; therefore, discovery of this melanoma cancer usually happens during an eye exam. Conjunctiva melanoma is found in the lining of the eyelid, while choroids melanoma is found in the pigmented coating of the eyeball. Both melanoma types are predominantly asymptomatic, but some patients report a scratchy feeling under the eyelid and a dark spot in their line of vision.
While somewhat rare, two subtypes of non-pigmented melanoma can be found: amelanotic melanoma and desmoplastic neurotrophic melanoma. Amelanotic melanoma usually appears as a pink or red lump, often overlooked or misdiagnosed as another affliction. Desmoplastic neurotrophic melanoma resembles a non-pigmented scar or cyst. When a scar seems to form in a location that was not injured, desmoplastic neurotrophic melanoma is suspected. Elderly patients with sun-damaged skin are the most likely candidates for developing this melanoma type. It often appears on the head and neck.