Color

In order to properly record or chart an abnormal finding, a common understanding of the various color changes associated with oral lesions must be achieved. Click on any link to see a picture of what is being described.

The vast majority of oral soft tissue lesions demonstrate some color change. This section will discuss the following predominant colors that are seen in oral soft tissue lesions: Pink, red, white, and combinations of red and white, blue, yellow, purple, gray, brown and black.

Color as perceived by the human eye represents light reflected from an object.

The human skin and oral mucosa are translucent. Light penetrates the covering epithelium to the various underlying layers of tissue (lamina propria and submucosa). Thus the covering epithelium is translucent.

As the incident light strikes each layer of tissue a portion is transmitted (allowed to pass on)....absorbed....scattered.....and reflected.

We perceive the normal oral mucosa as Pink in color due to the reflection of light striking the capillary bed.

Pigments are present in all layers and influence the tissue color. Normal tissue contains four primary endogenous pigments or biochromes:

  • oxyhemoglobin
  • reduced hemoglobin
  • melanin
  • lipofuscin

Hemoglobin is present in red blood cells. Two types: Oxyhemoglobin and reduced hemoglobin, reflecting the oxygen concentration. Oxyhemoglobin has more oxygen and imparts a bright red color. Reduced hemoglobin is less oxygenated and imparts a bluish color.

Melanin is brown pigment formed in specialized cells known as melanocytes. The pigment particles are transferred to malpighian cells of the epithelium. Since melanin is a significant diagnostic indicator, it will be discussed in detail with brown and black lesions.

Lipofuscin is yellow pigment of the submucosal fat that is also found in the cornified superficial layer of the epithelium, in sebaceous glands and blood plasma.

The blood contributes more to normal and abnormal tissue colors in the oral mucosa than any other single factor. The color imparted by blood is due primarily to hemoglobin.

The redness or blueness of tissue reflects the relative proportion of oxyhemoglobin and reduced hemoglobin in the underlying vessels. The arterioles contain approximately 95% oxyhemoglobin and 5,% reduced hemoglobin. The capillaries contain approximately 70% oxyhemoglobin and 30% reduced hemoglobin. The sub-papillary venous plexus contains approximately 50% of each.

Other factors related to the effect of blood on tissue color are:

  • The number of blood vessels concentrated in an area.....the more, the redder
  • The degree of dilatation or constriction of the vessels...The more dilated, the redder
  • The thickness of the overlying connective tissue and epithelium or the proximity of vessels to the surface...The closer to the surface, the redder.

Due to the complex interaction of the tissue biochromes and other secondary factors affecting tissue colors which this unit will discuss, it should be noted that single pure colors, as we normally interpret or see them, are rarely seen when dealing with soft tissue lesions.

Normal oral mucosa color is predominantly Pink but can vary from Pink to dark brown depending on the amount of melanin in the epithelium. Thus, rather than referring to the normal oral mucosal color as "Pink," it will be referred to as "normal color."

The vermilion borders of the lips, alveolar mucosae, soft palate, and pharynx show more variation in color. In people with little melanin, the lips may be more red, due to the prominent vascularity and nonkeratinization of the epithelium. In people with dense melanin deposits, the lips and gingiva may appear very dark brown. You have to look at each person's entire oral mucosa and establish in your mind what appears to be the "normal" color for that individual.

Normal mucosal color in elevated lesions indicates the pathology is submucosal in origin:

The surface mucosa has not been altered significantly, and the mucosal color is intact. Elevated lesions with a normal color most commonly manifest clinically as nonblisterform lesions, or as generalized lesions, tumors, nodules, or papules.Elevated normal color lesions may be due to one of several forms of underlying pathosis, most commonly hyperplasia, neoplasia, fluid accumulation, or cyst formation.

Hyperplasia

results from an increased quantity of normal tissue. In the oral cavity, normal color elevated lesions resulting from hyperplasia usually represent hyperplasia of connective tissue or bone.

Neoplasia

an abnormal new growth of tissue or a cellular infiltrate which may be benign or malignant. Thus a benign or malignant neoplasm may be normal color.

Fluid accumulation

in elevated normal color lesions is usually due to deep accumulation of fluid. If fluid accumulation is superficial, the lesion will be more translucent and the color will vary according to the color of the underlying structures.

Cysts

generally well localized lesions which represent a fluid-filled, epithelial-lined cavity.

Normal-colored, depressed lesions

Rare. However, such unusual lesions as developmental pits, clefts, or perforations will often be normal color. Atrophic scars may also have a normal color.

Some flat lesions of the tongue

may also be normal color. These are unique lesions which result simply from the loss of normal lingual papillae.

Tongue lesions which result from loss of papillae

may appear as dark normal color or red as the result of contrast with the surrounding papillae which are heavily keratinized. These should be considered normal color.

Melanin-related normal variations:

Melanin pigment causes normal variations from the Pink color of the oral tissues. This pigment is normally more prominent in African Americans, Asians, Native Americans and people of Mediterranean and Middle Eastern nationalities.

Melanin pigment concentrations are most common on the buccal mucosa, attached gingiva, and hard palate. Normal melanin pigmentation may be patchy or diffuse. It may cause the color of the mucosa to be brown to bluish-black, depending on the amount of melanin present. As discussed earlier, blood is the most significant factor influencing red color change. An increased quantity of blood to an area will result in an increased redness or erythema.

Redness or erythema - a variation of Pink

Redness or erythema may be localized or widespread, ranging from minute macules to involvement of large areas of skin or mucosa. Erythematous changes may occur without alteration in the morphology of the site. Red may be the predominant color in lesions of any morphology.

Redness or erythema may be caused by an increased quantity of blood, resulting from dilatation of existing blood vessels and/or proliferation of new vessels. Dilatation may be due to internal factors, such as naturally secreted substances that cause vasodilation or external factors involved with the inflammatory process that cause vascular dilatation and proliferation.

Lesions

Inside the oral cavity, the most obvious articles that appear white or a variation of white are the teeth. But bear in mind, approximately 50% of the soft tissue lesions of the oral cavity may appear as white lesions.

The most common causes of white lesions of oral mucosa relate to changes in the epithelium:

  • hyperkeratinization
  • acanthosis
  • necrosis
  • fluid accumulation.

Hyperkeratinization

one of the most frequent epithelial changes. Hyperkeratosis, the term for a thickening of the outer surface (keratin layer) of the epithelium is analogous to a callus on the skin. This excessive build-up and retention of surface cells alters the translucency of the epithelium by absorbing fluid from the environment and turning white. Chronic irritation and various other etiological factors can cause an alteration in epithelial cell maturation which also results in hyperkeratosis.

Acanthosis

Another common MICROSCOPIC epithelial change. Acanthosis is an increased thickening caused by hyperplasia of the prickle cell layer. When the epithelium becomes thickened by acanthosis, it becomes less translucent and more white because of decreased reflection of light from the normal capillary bed.

Necrosis

A common cause of white change, necrosis is death of cells in a localized area which can result in a slough when extensive areas of the epithelium become necrotic. Necrosis frequently follows moderate or severe inflammation but it may also be the result of physical or chemical trauma.

Increased fluid accumulation

Seen within the cells of the epithelium or beneath it, intracellular edema can cause a pale white appearance of extensive areas of oral mucosa. This is often associated with conditions involving the labial and buccal mucosa.

Extracellular accumulation of fluid

Beneath the epithelium, extracellular fluid can also alter light reflection resulting in a white color change. This holds for cysts or accumulations of other fluids such as edema or mucin.

Changes in the connective tissue

In addition to or instead of changes in the epithelium, an increased quantity of collagen or an alteration in maturity of collagen may result in white lesions. Increased quantity of collagen above the capillary bed decreases the reflection of red color to the surface. An example of this change can be seen in fibromas or scars. Some white lesions may be due to both epithelial and connective tissue changes.

The morphologic characteristics most often associated with white lesions are plaques and papules because these are primarily the result of epithelial alteration. Nodules and tumors are usually due to changes in the connective tissue. If allowed to persist they will frequently show a white change due to secondary hyperkeratinization. This hyperkeratinization is the result of mechanical friction from opposing structures during normal masticatory function.

Pallor is a unique variation of the white color change. Pallor is a minimal white change of the skin or mucosa most commonly seen in nonkeratinized and melanin-free sites such as the vermilion zones, fingernail beds, and conjunctival mucosa of the eyes. Pallor may be due to a decreased flow of blood, decreased hemoglobin content, or from an actual loss of hemoglobin.

Red and White Color

Red and white lesions commonly indicate the presence of inflammation.

Large ulcers, or depressed lesions are the most common morphologic characteristic associated with red and white color.

An inflamed lesion, which was originally red, may exhibit some white coloration as a result of necrosis and sloughing. Conversely, lesions originally white in color may undergo some red changes as a result of inflammation.

Some lesions such as superficial burns or fungal infections are white lesions initially, but when rubbed, result in the partial loss of the necrotic white surface. This leaves a denuded red area due to exposure of the capillary bed. Some large elevated lesions having a white hyperkeratotic surface undergo trauma which causes thinning and loss of the epithelial surface resulting in a red and white lesion. In either case the process of rubbing off the surface or traumatic thinning and denuding is called erosion.

Red and white color is frequently associated with dysplastic or malignant change in epithelium.

This is because dysplastic or frankly malignant epithelium is more friable and less durable than normal and thus more subject to injury. Also, malignant or dysplastic epithelium is less prone to heal normally once injured, therefore it retains a red and white injured appearance.

When determining the color of red and white lesions, the predominating color should be selected. If the red and white colors are approximately equal, the lesion should be indicated as red and white.


Gray Color

Gray is a relatively uncommon color in the mouth. Gray is not due to a biologic pigment but usually results from deposition of foreign material in the connective tissues. The gray color may be localized or diffuse.

Localized gray pigmentation

This usually results from implantation or deposition of foreign materials into lacerations or abrasions of the mucosa. The most common foreign particles encountered in the oral mucosa are amalgam or gold particles. These particles can be driven into the mucosa at high speed when finishing or polishing restorations. Amalgam is used in deciduous teeth as well as permanent. Amalgam fragments may be broken off teeth during extraction and fall into the extraction site leaving a gray discoloration after healing, provided they are close enough to the surface.

Diffuse gray pigmentations

These may result from heavy metal ingestion with subsequent systemic deposition of the material. This is seen in silver, lead, bismuth or mercury poisoning. Discoloration of this type can occur in both gingiva and unattached mucosa. The color may vary from gray to dark brown to black.

Natural brown pigments

Melanin or hemosiderin may occasionally appear as a gray color clinically. Since some of the reflected light from the material is absorbed as it passes through the thickness of the mucous membrane they appear gray rather than brown. This gray color change may be localized or diffuse. The natural grayness of some of the oral mucosa in African Americans is an example of a brown pigment, melanin, appearing as a gray color clinically.

Heavy concentrations of a pigment in the lamina propria may make the gray color very dark, almost black.

Gray color is most often associated with macules, since usually the amount of pigmented material is not sufficient to raise or otherwise alter the normal contour of the mucosa.

Blue Color

Blue is a relatively uncommon color in the mouth. It is the predominant color in approximately 13%, of oral lesions.

Blue is not a biologic pigment. However the color blue is usually associated with two types of lesions. Some cystic lesions containing clear fluid appear blue, some vascular lesions are blue and tattoos often are blue.

Cysts within soft tissue

Those which contain clear fluid such as mucin appear pale blue clinically. The exact reason for this blue appearance is not understood but may relate to absorption and reflection of light passing through the overlying soft tissue and the contents of the cyst itself.

Vascular lesions

These may appear blue when the blood within the lesion contains a large amount of reduced hemoglobin. This blue color can be seen through the translucent mucosa. The shade of this blue color may be altered by the thickness of the overlying mucosa. A darker blue or even reddish is seen with a more superficial lesion. A lighter blue is seen with a deeper lesion.

Cystic and vascular lesions are relatively large blisterform lesions. The morphology most often associated with blue color is a bulla. This does not mean always.

Tattoos from foreign bodies may appear as blue macules.

Purple Color

Purple is also a relatively uncommon color in the mouth.


Purple color is often associated with vascular lesions and deposition and interaction of pigments.

Vascular lesions

Some appear blue, others may appear purple. The perception of purple is due in part to the basic bluish color being modified by the normal Pink or reddish mucosa. Purple color may also be due to the combination of both oxygenated and reduced hemoglobin in the blood.

Deposition and interaction of pigments

Pigments from breakdown products of extravasated blood may cause a purple discoloration. Purple lesions resulting from deposition and interaction of pigments are usually macules, nodules or tumors.

Purple vascular lesions are often bullae.

 

Bleeding into blisterform lesions and hematomas may cause a purple discoloration.

Brown Color

Brown is a relatively uncommon color in the mouth.

Brown coloration may be caused by melanin or hemosiderin.

Brown pigmentation due to melanin usually appears as a macule but may also appear as a nodule or tumor.

Hemosiderin

may also be a source of brown coloration. You will recall that hemosiderin is a breakdown product of hemoglobin following extravasation of blood. Brown color resulting from hemosiderin is most frequently associated with crusting and drying of ulcerated lesions on the vermilion zones and skin.

Black Color

Black is a relatively uncommon color in the mouth. Black is the predominant color in approximately 7% of oral lesions.

Darkly colored foreign materials

Beneath the oral mucosa foreign particles may appear as black. Amalgam or gold particles beneath the oral mucosa, although usually Gray, often appear as black. Black lesions caused by foreign body deposition are usually macules.

Alteration in blood pigments

Loss of epithelium in ulcerative lesions may allow the escape of blood onto the surface of the mucosa. If an alteration in blood pigments occurs, such as with oxidation and drying, a black color may appear in the crust. Black lesions caused by breakdown of blood pigments are usually macules.

Extravasated blood

Blood in the tissue in the form of a hematoma undergoing degradation may appear as a black lesion (or a "black and blue" mark) .

Tissue death or necrosis

With invasion of saprophytic organisms, gangrene occurs. This process is characterized by black color. When necrosis and gangrene of tissue result in a black color, the lesion usually undergoes a macular change. As the dead tissue sloughs, a depressed lesion with a black periphery is formed.

Heavy concentrations of foreign or biologic pigments

This may result in a black appearance. For example, melanin, which is brown, in very heavy concentrations, may appear black. Dense concentrations of melanin pigment causing a black lesion usually appears as a macule, but may also appear as a nodule or tumor.

 

 

Yellow Color

Yellow is a relatively uncommon color in the mouth.

Yellow color may be caused by lipofuscin (the pigment of fat). It may also result from other causes such as accumulation of pus, aggregation of lymphoid tissue, exudation of serum, degeneration of blood pigments, lipid containing structures, neoplasms and extrinsic stains

Accumulation of pus

Pus from degenerating leukocytes takes on a yellowish tinge seen in acute inflammation. Thus a yellow color may be seen in association with ulcers or pustules.


Lymphoid tissue

Lymph tissue located superficially beneath the oral mucosa may present as yellow to yellow-orange papules or nodules, a common finding on the posterior tongue or pharynx.

Serum

Serum is normally a yellow or straw-colored fluid. Exudation of serum in an inflammatory reaction may reach the surface if loss of epithelium has occurred. If drying occurs, as on the lips, a crust may form. This crust may take the form of a rough, yellowish plaque or may be seen at the periphery of an ulcer.

Degeneration of blood pigments

Degenerating blood pigments , particularly in the formation of bilirubin, may result in a yellow color either localized or diffuse.

Excess bilirubin in the tissues

A diffuse yellow color may occur if there is breakdown of bile pigments as in liver disease, blockage of the bile ducts, or excess bilirubin formation in hemolytic disease. This condition is jaundice and is a diffuse macular change.

Lipid, or fat, is yellow

Accumulation of fat near the surface such as occurs in obesity, in neoplasms, and as a result of abnormalities of lipid metabolism may cause a yellow color. Normal lipid-containing structures, such as Fordyce's granules, usually appear as yellow papules.

 

A fat-producing neoplasm

Localized accumulation of fat in neoplasms produces a yellow lesion with the morphologic characteristics of a nodule or tumor.

Abnormalities of lipid metabolism

Localized deposition of fatty substances may occur in systemic metabolic diseases. These present as yellow papules, nodules, or plaques.

Extrinsic stains

Staining of tissues, especially of white lesions may cause a yellowish color. For example, use of tobacco may cause a white lesion to assume a yellowish color. Extrinsic stains usually involve hyperkeratotic areas such as plaques or nodules. When this occurs, white should be considered as the predominant color.

 

Translucent lesions (totally transmits light)

Clinically, it is usually quite simple to distinguish between blisterform and nonblisterform lesions by palpation. You will recall from the morphology section that many blisterform lesions can be distinguished from nonblisterform lesions by their translucent quality. Lesions which appear translucent are blisterform. The translucency as well as the associated color of the lesions can be significant factors in differential diagnosis. Both the translucency and associated color change of a lesion are accurate indicators as to the nature of the fluid content and its proximity to the surface.

Translucent Pink lesions

These usually indicate an accumulation of a relatively clear fluid such as serum, mucin, or lymph. The covering mucosa has a relatively normal thickness which allows blood in the overlying tissue to color the lesion.

Translucent blue

These lesions may represent clear fluid or blood accumulation. The blue color from clear fluid accumulation indicates a superficial lesion covered by a thin mucosa which causes absorption of most of the visible wavelengths of light except blue which is reflected.

Translucent Red or purple

These lesions usually indicate blood accumulation which may be either intravascular or extravascular.

Most lesions that demonstrate a translucent quality are bullae or vesicles.

Summary

This section has reviewed the nine colors associated with oral soft tissue lesions. Pink, red, white, and combinations of red and white are the most common colors encountered whereas blue, yellow, purple, gray, brown, translucent and black are uncommon colors for oral lesions. If you want to return to any of the color sections, just click on the color in this paragraph. Return to TOP of color section.

Pure colors are extremely rare when dealing with soft tissue lesions. The primary and secondary factors causing and influencing tissue colors are varied and complex. Blue and gray lesions may be extremely difficult to distinguish. Fine distinctions between colors are the result of perception of color by the observer. Thus what is Pink to one person may be red or reddish to another. Similarly blue and purple distinctions are not always easy to make.

In general, the more common colors such as Pink, red, white and red and white are less significant in leading to a specific diagnosis; however, colors such as blue, gray, Yellow, purple, black, and brown may be highly significant in making an accurate clinical diagnosis.

 

A final word about clinical diagnosis of oral soft tissue lesions

With most clinical lesions, it is impossible to make a final diagnosis with absolute certainty. As your clinical experience broadens, and you mature in your judgement, you will acquire significant expertise that will make your clinical diagnoses frequently accurate. NOTHING, HOWEVER CAN SUBSTITUTE FOR A BIOPSY (INCISIONAL OR EXCISIONAL). If the lesion is present under your observation for 2-3 weeks and you cannot point to a specific cause, you should biopsy the lesion. The procedure is simple, safe and the peace of mind for you and the patient is well worth the expense.

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