Find us on Facebook!

Dermatology Library

M

Macule:

A flat spot or patch of skin that is not the same color as the surrounding skin.

Malignant:

When referring to cancer, malignant means the ability to grow and spread in an uncontrolled manner beyond the local confines of the tumor. Its opposite, "benign," refers to a growth that is non-cancerous.

*Malignant Melanoma: See: Melanoma

Margin:

In skin cancer surgery, the amount of normal-appearing tissue removed around the tumor. Margin is usually measured in centimeters.

Tumor Thickness (millimeters) Excisional Margin (centimeters)
In situ melanoma 0.5
less than 1.0 1.0
1.0-4.0 2.0
more than 4.0 at least 2.0

Surgical margin may be modified in individual patients for medical or esthetic reasons. The main goal is complete removal of the melanoma.

See Thickness for a discussion of the relationship between tumor thickness and 5-year survival after treatment.

Also see: Skin Cancer, Melanoma

Melanin:

Skin pigment (substance that gives the skin its color). Dark-skinned people have more melanin than light-skinned people.

Melanocytes:

Cells that make the skin pigment melanin. Melanin is made in small granules, called melanosomes, within the melanocyte. Melanin is then transported to cells of the outer skin (keratinocytes), where the melanin is seen as "color" of the skin.

Melanoma:

Melanoma is a type of cancer that begins in the skin. It is completely curable when detected early, but can be fatal if allowed to progress and spread. Cancer is a condition where one type of cell grows without limit in a disorganized fashion, disrupting and replacing normal tissues and their functions, much like weeds overgrowing a garden. Melanoma is a cancer of the pigment producing cells in the skin, known as melanocytes. Normal melanocytes reside in the outer layer of the skin and produce the brown pigment melanin, which is responsible for the color of our skin. Melanoma is when melanocytes become cancerous, grow, and invade other tissues.

Also see topics in: Skin Cancer

Melasma:

Melasma Melasma (aka cholasma or mask of pregnancy) is a non-cancerous (benign) disorder of unknown cause that causes dark (hyperpigmented) patches, primarily on the face. The condition is marked by brown patches that worsen in response to increases of the hormone estrogen, such as during pregnancy or with the use of birth control pills. Other medications, such as anti-seizure medications, may also cause melasma. Increased sun exposure can also be a cause.

Melasma Although the condition is more common in women, men can also have melasma. People with darker skin types are generally more likely to have it. Also, family history of melasma increases the likelihood of developing the condition.

The dark patches of melasma most commonly affect the face, particularly the sides (lateral portions) of the cheeks and sometimes the skin above the lips.

Protect your skin from sun exposure to prevent worsening, and use a combined UVA and UVB sunscreen year round.

Treatments consist of bleaching creams such as hydroquinone. Retinoids such as tretinoin cream may also be used in combination with bleaching agents. Chemical peels and microdermabrasion can also be helpful. Another option is azelaic acid.

Submitted by: Casey A. Nichols, MSN, ARNP-BC

Metastasis:

The spreading of disease from one part of the body to another part. Melanoma metastasizes most often to lymph nodes, liver, abdomen, lungs, bone, skin, heart, and brain.

Microdermabrasion:

See: Dermabrasion

Minoxidil:

See: Hair Loss

Mohs surgery:

In certain situations, your dermatologist may refer you for a specialized technique called Mohs micrographically controlled surgery. In this method, performed by specially trained dermatologic surgeons, the skin cancer is removed under local anesthesia in an office setting and microscopic sections are prepared on slides while you wait. Your Mohs surgeon examines the slides to determine if all the cancer cells have been removed. If not additional layers are taken until the cancer is completely excised. The advantage of this technique is that a minimum amount of tissue is removed and all the edges of the specimen are carefully studied. This method has a high cure rate, but is not required for all skin cancers. In general, most dermatologists agree that recurrent skin cancers (skin cancers that were previously treated and have come back, incompletely removed skin cancers, large skin cancers, and skin cancers in cosmetically important areas), may benefit from the Mohs technique. After the skin cancer has been removed using this method, it maybe allowed to heal naturally or reconstructive surgery using a skin flap or skin graft may be performed.

Also see: Skin Cancer, Dermatologic Surgery

Moles:

Everyone has moles (also known as "nevi"), sometimes 40 or more. Most people think of a mole as a dark brown spot, but moles have a wide range of appearance. They can be raised from the skin and very noticeable, they may contain dark hairs, or they may be dangerous. Moles can appear anywhere on the skin, alone or in groups. They are usually brown in color and can be various sizes and shapes. The brown color is caused by melanocytes, special cells that produce the pigment melanin. Moles probably are determined before a person is born. Most appear during the first 20 years of a person's life, although some may not appear until later in life. Sun exposure increases the number of moles. Each mole has its own growth pattern. At first, moles are flat and tan, pink, brown or black in color, like a freckle. Over time, they usually enlarge and some develop hairs. As the years pass, moles usually change slowly, becoming more raised and lighter in color. Some will not change at all. Most moles will slowly disappear, seeming to fade away. Others will become raised so far from the skin that they may develop a small "stalk" and eventually fall off or are rubbed off. This is the typical life cycle of the common mole. These changes occur slowly since the life cycle of the average mole is about 50 years. Moles may darken, with exposure to the sun. During the teen years, with birth control pills and pregnancy, moles often get darker and larger and new ones may appear.

Molluscum contagiosum:

Molluscum contagiosum Molluscum contagiosum is a viral infection of the skin or occasionally of the mucous membranes. The infection is most common in children aged one to ten years old. Molluscum contagiosum affects any area of the skin but is most common on the body, arms, and legs. It is spread through direct contact or shared articles of clothing.

In adults, molluscum infections are often sexually transmitted and usually affect the genitals, lower abdomen, buttocks, and inner thighs. In rare cases, molluscum infections are also found on the lips, mouth, and eyelids.

The time from infection to the appearance of lesions ranges from 2 week to 6 months, with an average incubation period of 6 weeks. Diagnosis is made on the clinical appearance; the virus cannot routinely be cultured.

Molluscum contagiosum lesions are flesh-colored, dome-shaped, and pearly in appearance. They are often 1-5 millimeters in diameter, with a dimpled center. They are generally not painful, but they may itch or become irritated. Picking or scratching the bumps may lead to further infection or scarring. In some cases, eczema develops around the lesions. They may occasionally be complicated by secondary bacterial infections.

The central waxy core contains the virus. In a process called autoinoculation, the virus may spread to neighboring skin areas. Children are particularly susceptible to auto-inoculation, and may have widespread clusters of lesions.

Individual molluscum lesions may go away on their own and are reported as lasting generally from 6 to 8 weeks, to 2 or 3 months. However via autoinoculation, the disease may propagate and so an outbreak generally lasts longer with mean durations variously reported as 8 months, to about 18 months, and with a range of durations from 6 months to 5 years.

Treatment is often unnecessary depending on the location and number of lesions, with no single approach shown to be convincingly effective. The most commonly used treatments are:

Aldara, which is a form of immunotherapy, triggers your immune system to fight the virus causing the skin growth. Aldara is applied 3 times per week, left on the skin for 6 to 10 hours, and washed off. A course may last from 4 to 16 weeks.

Surgical treatments include cryosurgery, in which liquid nitrogen is used to freeze and destroy lesions, as well as scraping them off with a curette. Application of liquid nitrogen may cause burning or stinging at the treated site, which may persist for a few minutes after the treatment. Scarring or loss of color can complicate both these treatments. With liquid nitrogen, a blister may form at the treatment site, but it will slough off in two to four weeks. It should be noted that cryosurgery and curette scraping are not painless procedures. They may also leave scars and/or permanent white (depigmented) marks.

Submitted by: Casey A. Nichols, MSN, ARNP-BC

Monkey Pox:

Monkeypox is a rare viral disease that is found mostly in the rainforest countries of central and west Africa. The virus can spread to humans from an infected animal through an animal bite or direct contact with the animal's lesions or body fluids. Although it is much less infectious than smallpox, the disease also can be spread from person to person through large respiratory droplets during long periods of face-to-face contact or by touching body fluids of a sick person or objects such as bedding or clothing contaminated with the virus.

Mouth Care:

Gum disease, halitosis, mouth ulcers and sensitive teeth are all problems which fall under oral health and which do not necessarily require a trip to the dentist. Each one is discussed in detail below.

GUM DISEASE (PERIODONTAL PROBLEMS)

Periodontal problems affect the supporting tissues of the teeth and are related to poor gum management. They constitute the major dental risk to the adult population. The most important cause is accumulation of plaque which leads to bacterial growth and subsequent inflammation. There are two major conditions, gingivitis and the more severe periodontitis.

GINGIVITIS

Plaque which accumulates at the tooth gum junction harbours various bacteria which produce metabolites. These metabolites, which include inflammatory agents, are secreted into the local gum. This results in capillary dilatation and oedema, the redness and swelling which are symptoms of the condition.

If the plaque and its associated bacterial colony are not removed, the degradatory process continues leading to decreased venous return and a bluish tinge of deoxygenated blood being observed.

PERIODONTITIS

Gingival epithelial cells are attached to tooth enamel at the gum tooth junction. As a consequence of bacterial action, there may be loss of this epithelial attachment causing the development of 'pockets'. These may be 3-4mm deep and they harbour food particles and bacteria. This also leads to gum recession.

If this is not resolved the condition worsens. The marginal gingivae is normally attached to the teeth by a network of collagen fibres which is called the periodontal ligament. This ligament may become weakened and alveolar bone is irreversibly lost.

The tooth becomes loose and there is a danger of further bacterial attack with the development of abscesses, and eventual tooth loss.

HALITOSIS

Some degree of bad breath is normal first thing in the morning. This is the result of reduced tongue activity and salivary flow during the night. There is a build up of a high concentration of malodorous sulphur compounds produced by bacteria overnight which results in halitosis. Mouth breathers also suffer more from morning halitosis.

Bad breath at other times may indicate a problem. As many as 85 per cent of halitosis cases are caused by problems in the oral cavity. Gingivitis, periodontitis and caries are common causes, while oral cancer may be implicated in extreme cases.

However, non-oral causes are well known. These include sinusitis, tonsillitis and rhinitis. Gastric problems as well as diet may be the cause. Highly odorous foods and drinks give off smells which may 'leak' from the stomach. These include onions, garlic, spicy foods and alcohol. These are also excreted from the lungs giving rise to halitosis many hours after ingestion.

Halitosis of short duration may be due to the stomach being empty. Other rarer causes include tuberculosis and acute serious illness such as typhoid fever.

APHTHOUS ULCER

About a fifth of the population suffer from mouth ulcers in any one year. US surveys indicate they are most common in patients who are stressed and that a slightly increased proportion of females are affected.

Single isolated traumatic ulcers are often due to catching the gum with the toothbrush or hard food.

The cause of recurrent aphthous stomatitis is largely unknown. Many factors appear to be involved, including genetic predisposition, hypersensitivity to normal mouth bacteria, food allergies, hormonal changes, systemic disease and nutritional deficiency. Recent research has implicated the immune system and a specific trigger event (stress, trauma, female cycle).

Aphthous ulcers range from 0.3-3cms in diameter and occur on the non-keratinised mucosal surfaces of the mouth such as the cheeks, tongue and gums. They have depressed round grey area and a red erythomatous edge. They may be extremely painful, inhibiting eating.

HYPERSENSITIVE TEETH

Many patients develop teeth sensitivity and it may be related to gum recession, exposing the cementum/enamel junction. Other cases include excessive brushing with a hard toothbrush and use of abrasive toothpastes or powders. Gum recession is common in old age.

Reversal of gum recession should be the major aim of treatment. Sensitivity caused by the nerves being more accessible may be treated by specific toothpastes designed to 'block the pores' in the enamel. The strontium ion is believed to block nerve access and is thus useful.

A second mechanism is to reduce nerve transmission using the potassium ion. Fluoride is also incorporated in some toothpastes designed for sensitive teeth.

Applying these toothpastes directly to teeth with a finger is more effective than traditional brushing.

Mucocutaneous candidiasis:

A mycotic infection of the skin and mucous membranes usually caused by the yeast, Candida albicans. However, other Candida species are occasionally responsible. It is a common disorder that affects all age groups, with no sex, race, or ethnic predilection. Mucocutaneous candidiasis is more common in persons who wear dentures, have diabetes mellitus, and in those immunocompromised by disease or by therapy. Most patients have disease limited to the cutaneous surfaces, especially areas of skin folds. However, immunocompromised persons may develop extensive cutaneous involvement. In some patients a serious, even life-threatening, systemic infection may develop. Systemic candidiasis is not addressed here.

Mucous membrane involvement may be a marker for an immunocompromised state. The presence of oral candidiasis, especially in adults, may be an initial manifestation of diabetes mellitus, leukemia, lymphoma, malignancy, neutropenia, and HIV infection. Genital candidiasis may affect the vulva and vaginal area, as well as the perineal and groins, causing candidal intertrigo. Candidiasis may also affect the nail unit, particularly the nail plate and paronychial area.

Mycosis Fungoides:

Mycosis fungoides is the most common of the cutaneous T-cell lymphomas, a group of rare cancers that grow in the skin. Sezary syndrome, a more rare form, occurs in about 5% of all cases of mycosis fungoides. In the United States, approximately 1000 new cases of mycosis fungoides occur per year. It affects men twice as often as women, and is more common in African Americans than in Caucasians. Mycosis fungoides can begin at any age, but the most common age is 50 years old. The cause of the disease is unknown.

Symptoms - Mycosis fungoides progresses in stages, which are defined by the skin symptoms:

  • Patch phase - The skin has flat, red patches; in dark-skinned individuals these may appear as either very light or very dark patches. They are very itchy. Some areas may be raised and hard (plaques). The patches and plaques often appear on the buttocks, groin, hips, under the arms, and on the breasts/chest.
  • Skin tumors phase - Red-violet raised lumps (nodules) appear and may be dome-shaped (like a mushroom) or be ulcerated.
  • Skin redness (erythroderma) stage - In addition to the patches and tumors, the individual's skin developed large red areas that are very itchy and scaly. Skin folds in the face may thicken, and skin of the palms and soles may thicken and crack.
  • Lymph node stage - In this stage, mycosis fungoides begins to move to other parts of the body. The first parts affected are the lymph nodes, which become inflamed, and often cancerous. Cancer may spread to the liver, lungs, or bone marrow.

Diagnosis - Typically there is about 6 years from the time symptoms begin to the diagnosis of mycosis fungoides. Confusion with other conditions is common. A sample of the skin can be taken (skin biopsy) and examined for the disease. Other laboratory tests can be done to determine the progression of the cancer.

Treatment - If mycosis fungoides is in the early stage, treatments such as steroid creams, chemotherapy applied to the skin, or electron beam radiation may be used. The goal is to put the cancer in remission, which often lasts a long time.

If an individual's disease does not respond to the skin treatments, or the disease has progressed to the tumor stage, systemic treatments such as recombinant alfa interferon or chemotherapy may be used. There is no cure for mycosis fungoides, so how long a person survives with the disease depends on how far it has spread by the time it is diagnosed and treatment begins.

Submitted by: Laura L. Mays, PA-C

Mycotic Infection:

Fungal infection