melanoma | medical plaintalk

In ancient mythology, moles were dark spots sent by jealous gods to spoil the faces of beautiful people. Later, moles became signs that the soul had fled the body, a notion that shows up today in Halloween witch masks with hairy warts sprouting from noses. In the 1800s, imitation moles made of leather, velvet and mouse fur covered pox scars in the aristocracy and led to their rebranding as beauty marks. Modernity continued this tradition with some famous stars like Marilyn Monroe enhancing their moles cosmetically. However, modernity also gave rise to the fear of moles because of worry about the most serious form of skin cancer, the melanoma. Most people have moles somewhere on their body. How do you know which ones to worry about?

Melanocytes: the origin of dark spots

Before you begin worrying, you need to know what you are worrying about. The problem with moles is that, though the vast majority are quite benign, they come from the same type of cells that give rise to the dreaded melanoma. These cells are called melanocytes, one of three types of skin cells. They make the pigment melanin that gives skin its color and protects it against ultraviolet light, the kind that produces sunburn. Melanocytes store melanin in little capsules inside themselves, ramping up production when the skin is exposed to sunlight, and distributing it to the outer skin layer where cells called keratinocytes absorb it. Moles, which are technically known as melanocytic nevi, are clumps of melanocytes which appear as dark, often raised spots anywhere on the skin. They are regular shaped with smooth edges, evenly colored, and generally less than a quarter of an inch in diameter. Moles are not freckles, which are discrete spots of reddish-brown keratinocytes that appear mainly in very fair-skinned people because the melanin distribution process in their skin is uneven.

Moles: the cloning of well behaved rogue cells

Babies are rarely born with any moles. Melanocytic nevi begin to appear in childhood and continue for several decades, peaking in the thirties. Most people have between 10 and 40 moles by adulthood. Sometimes they begin to reverse and disappear. Recent research suggests that a mole appears when a rogue melanocyte begins to clone itself. This sounds like the same process that begins cancer, and, indeed, initial melanocyte growth involves genetic changes similar to those seen in cancer cells. But in the case of the mole, there appear to be controlling processes at work that prevent continued growth and organize the cells into well-defined architecture characteristic of non-cancerous growths. But will it turn into a melanoma – a cancer which may spread both locally and distantly?

Melanomas: Rogues without controls

Most moles are and remain benign throughout life. Melanomas, though, are increasing in frequency in recent decades. Projected numbers of new melanoma diagnoses in the US in 2019 estimate over 96,000 cases, more in men than in women. Deaths from melanoma will exceed 7,200. Melanomas are twenty times more common in white skinned people than in dark skinned. About 25-30% of these melanomas will arise in previously stable, benign moles, but it is not at all clear that the mole is the source. They may be just as random in their appearance there as they are in any other part of the body. Melanomas also begin with rogue melanocytes, but they lack the control mechanisms of the offspring of the melanocyte that gives rise to a mole. They are biologically different from the cells in moles.

Markers for melanoma risk

What increases the risk for melanoma development? Fair skin and freckling, a family history of melanoma, chronic unprotected sun exposure, large numbers of nevi, and biopsies showing irregular (dysplastic) features under a microscope. Large number of moles – in the range of 100, also increase the risk that a melanoma will appear in a previously benign spot. Some melanomas appear in unexposed areas of the body, inside the mouth and in the eye, suggesting that they are different biologically from melanomas that occur in sun-damaged skin.

Early recognition helps

Early recognition of a melanoma improves the outcome. Five-year survival rates when the tumor is localized in the skin is 98%. With spread to regional lymph nodes, survival falls to 68% and down to 23% with spread to distant lymph nodes and other organs. Overall five-year survival is 92% and improving with the advent of newer forms of treatment based on immune attack of the tumors.

Early recognition of melanoma depends on two things – knowing your own moles and examining them and the rest of your skin for any changes on a regular basis. Self-examination means using a mirror or asking a partner to help with scrutiny of your head and backside. What are you looking for?

New spots with irregular color or borders. But every new spot, especially in older people, is not cause for worry. Many are so called age spots – flat, brown, over-pigmented areas. Others are overgrowths of keratinocytes called senile or seborrheic keratoses.
Change in old moles, especially irregularities in color or shape. Some melanomas may be pale, not dark. Some may have multiple shades. Some are relatively smooth but others may be bumpy.
Growth in size happens to moles at times, particularly with hormonal change, or with sun exposure, and growth alone is a poor predictor of whether or not a mole has transformed to a melanoma. Growth with change in color or border irregularity is more worrisome.
A bleeding mole, or failure to heal if the surface is disturbed.

A biopsy is the only way to know for certain that what a change in a mole, or a suspicious new spot represents, and regular examination by a dermatologist eases worry, especially if you have a family history of melanoma or an unusually large number of moles. And it is never too late to protect your skin from the sun, by avoiding exposure during the height of the day, by covering skin with clothing, and using sunscreen in unavoidably exposed areas.

Babies arrive in the world with soft, smooth, and usually flawless skin. Old men and women leave the world wrinkled, mottled, spotted, and scarred. In between, the skin replaces itself many hundreds of times and in the process accumulates enough DNA damage to make skin cancer the most common of all cancers, with more than 2 million cases occurring in the United States each year. Fortunately, most skin cancers stay put in the locations where they start. They don’t invade nearby tissues and don’t spread through the base of the skin to travel to other parts of the body. Skin cancer is largely curable by removal alone.

Different skin cells and different skin cancer names

The three most common types of skin cancer arise from cells that grow in the epidermis, or outermost layer of the skin. The inner layer of the epidermis is made up of basal cells. Basal cells regularly reproduce themselves in order to make squamous cells, which are replacement skin cells and form a middle epidermal layer. This layer also contains cells called melanocytes. Melanocytes produce melanin, the pigment that gives skin its color. The outer layer of the epidermis consists of dead skin cells that are constantly being shed. The most common skin cancers come from these three types of skin cells: basal cells, squamous cells, and melanocytes. All three types of cancer are more common in fair-skinned, light-haired, light-eyed people. All three are also related to lifetime sun exposure.

Basal cell skin cancer

Basal cell cancer is the most common type of skin cancer, accounting for 80 to 90 percent of reported skin cancer cases. It is also the most benign skin cancer. Basal cell cancers begin with errors in a cell’s DNA, which serves as instructions for building squamous cells from basal cells. The abnormal cells that are created by this damaged DNA form a tiny area of skin that is different from surrounding normal skin. Typically, it looks like a little dome, with a waxy, pale appearance. Over time it may develop tiny blood vessels around it. It might bleed easily or develop a sunken center or a crusted top. Sometimes the color may be a little darker or rosier than that of the surrounding skin.

Basal cell cancers grow slowly and very rarely travel to other parts of the body. That said, they can invade nearby tissues, and the earlier they are removed, the less likely they are to recur (and the smaller the scar caused by their removal will be). Basal cell cancers occur most commonly on areas of the body exposed to the sun, especially the scalp, forehead, and corner of the nose. They are also more common in people who have been intermittently exposed to the sun without protection. Basal cell cancers take many years to develop, and by age sixty-five, about 50 percent of the population will have developed at least one such cancer. Within five years of treatment of one basal cell cancer, one-half of patients will develop a second one. Because of the popularity of tanning, both indoors and out, basal cell cancers are now appearing in some people before middle age.

Squamous cell skin cancer

Squamous cell cancers can occur in areas of the body that are not generally exposed to the sun, like the mouth and the genital region. However, when squamous cell cancers appear on the skin, they typically develop in areas that show other signs of sun damage—wrinkling, freckling, mottling, thinning, and sagging. They may also evolve from solar, or actinic, keratoses, which are considered precancerous markers of sun damage. Usually appearing as small red spots (under a quarter of an inch in diameter), solar keratoses have some white scaling on their surfaces. Some are sore and tender, and thickening with increased tenderness can indicate a progression to a skin cancer. Squamous cell cancers can be flat and scaly patches of skin or firm, red nodules or non-healing sores. Unlike basal cell cancers, squamous cell cancers, particularly those on the lip, can penetrate deeper layers of skin and travel to other parts of the body by way of the lymphatic system, though this spread is uncommon. If many precancerous lesions are present, treatment with chemotherapeutic creams helps prevent cancer development.

Melanomas

Like basal cell and squamous cell cancers, melanocyte cancers, which are known as melanomas and appear similar to moles, more commonly occur in fair-skinned people and are also related to sun exposure. It is no coincidence that the highest rates of melanoma in the world are in Australia and South Africa, two highly sunny areas colonized by fair-skinned people who are genetically better suited to the gray skies of northern climates.

Melanomas must be distinguished from normal moles, which develop in virtually all people. The average adult has twenty-five moles with varying degrees of pigmentation. Many “rules” exist for helping physicians decide whether a mole might be cancerous. For example, moles that are asymmetrical in shape and color, have irregular margins, and are larger than a pencil eraser are often considered suspect. However, none of these “rules” is a reliable way to tell if a mole is cancerous. More reliable suspicions are generally based on observations concerning mole development. The development of a new mole, particularly on the back or the legs, that grows over a number of years is definitely something that should be discussed with a physician.

A full 70 percent of melanomas are what are termed superficial spreading melanomas and are curable if caught when they are less than 1mm thick. Another 7 to 10 percent of melanomas, those that are deep blue-black or purple nodules, tend to spread more readily to other parts of the body. Rarer yet are melanomas in odd locations like the eye, under a nail, on the palm of the hand, or on the sole of the foot. These, too, are more dangerous.

Like basal cell and squamous cell cancers, the treatment for a melanoma is removal. There are a variety of different ways to remove skin cancers, ranging from scraping and cauterizing to a surgical excision with microscopic monitoring to find the edges of the tumor. Cure rates are high—in the 98 percent range, particularly when the tumors are small. If a tumor does spread to nearby tissues, it can still be cured, though with more surgical scarring. Metastatic melanomas do not respond well to conventional cancer treatments as a rule but may react differently to newly developing targeted immunological treatments.

Screening for skin cancer: no controversy

In contrast to the confusion surrounding screening tests for some other types of cancer, clarity is the mark of medical advice about skin cancer. It helps if you know what to look for and to seek a medical opinion about any suspicious skin spots. Most often, doctors will recommend biopsy of a suspicious lesion as the surest way to make a diagnosis, and patients can expect that removal will be part of the cure for any cancers that are found. You won’t ever regain the skin of a newborn, but you do not need to have skin cancer.

Your role in skin cancer prevention

• Beginning early in life, protect your skin, particularly the skin on your face, scalp, ears, lips, back , arms, and hands. Use hats, shirts, and sunscreen (at least 30 SPF) to help block the harmful rays of the sun.
• Avoid prolonged sun exposure when the sun is high in the sky.
• At least once in middle age, have a professional examination of all your skin. If you are fair-skinned, and/or have sun damaged skin, heed your physician’s advice if he suggests more regular checkups. The American Academy of Dermatology sponsors free screening exams every May.
• Keep an eye on your skin and have new, enlarging, color-changing, non-healing or bleeding spots checked by a professional.

Posted by medical plaintalk

Posted by medical plaintalk