Disorders of Hair, Nails, and Pigmentation

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[edit] Disorders of Hair, Nails, and Pigmentation

Janet Roberts

Phoebe Rich

Frank Parker

[edit] DISORDERS OF HAIR

[edit] Alopecia

The term alopecia means hair loss or baldness and requires an adjective to specify a given pathology. Hair loss is a common complaint, often confusing to both the patient and the treating physician. It can be emotionally devastating to some people.

[edit] Hair Physiology.

Understanding hair growth cycles is essential to diagnosing hair disorders.^[1] The hair shaft is keratin protein produced by hair matrix cells at the base of each follicle. These cells divide every 12 hours, which makes them vulnerable to physical insult. The active growth phase of hair follicles is the anagen phase and may last from several months to several years. The length of the growth phase is genetically determined, varies with different hair follicles in different parts of the body, and determines the length to which a person's hair will grow. At the end of the anagen phase, an unknown signal causes the hair follicle to undergo a brief transition or catagen phase, lasting only 2 to 3 weeks. After the catagen phase, the hair follicle enters a relatively long resting, or telogen, phase lasting 2 to 3 months. During this time a new anagen hair is forming beneath the resting hair. As it grows, the telogen hair is shed. Normally about 90% of scalp hair is in anagen phase. Approximately 100 scalp hairs are shed daily and are minimally observed by an individual.

[edit] History of Hair Loss (Box 92-1).

The following points must be clarified: (1) whether the first observable change noticed by the patient is shedding (increased loss of hairs coming out by the roots), breakage (increased loss of hairs because of hair shaft fracture above the root level), or thinning (having less hair to cover the head); (2) duration, extent, and distribution of hair loss; (3) family history of hair loss; (4) associated abnormalities of nails and skin; (5) specifics of chronic or acute illnesses, surgeries, nutrition, and medications; (6) in females, hormonal status and hirsutism; and (7) cosmetic processing.

[edit] Physical Examination.

The hair and scalp over the entire head must be examined carefully in a strong light. Check for excessive hair (hirsutism) or lack of hair in remote areas and note any associated lesions of skin, mucous membranes, and nails. Note the extent and pattern of hair growth on the scalp and body and any evidence of scalp disease, such as erythema, scaling, crusting, pustules, atrophy, telangiectasias, and presence or absence of follicular orifices. Note any discrete nodules or growths, either superficial or deep, which may suggest malignancy, either primary or metastatic, to the scalp. Short hairs, whether blunt (broken off or cut) or tapered (regrowing or miniaturizing hairs) are more easily visualized when viewed against a card of a contrasting color—white for pigmented hairs and black for gray or white hairs.

[edit] Laboratory Findings

Microscopic examination of the hair is indicated in patients with breakage problems such as tinea capitis, hair shaft abnormalities, or cosmetic breakage.

In preparing hairs to evaluate for fungus, pluck a few short or broken hairs and cover with potassium hydroxide (KOH) for 15 to 20 minutes. This procedure dissolves the hair keratin and allows for visualization of the fungal elements under high dry magnification. When preparing a hair mount to look for suspected hair shaft abnormalities, the goal is clear visualization of the hair shafts without optical distortion; so place segments of hairs on the slide and cover with a drop or two of Permount (available from most laboratory supply companies).

[edit] TYPES OF ALOPECIAS

Diseases resulting in alopecia are classified as scarring or nonscarring to facilitate making the correct diagnosis (Table 92-1). The nonscarring classification can be divided further into those conditions in which the hair is lost because of hair shaft breakage, hair shedding with the roots attached, and hair thinning with little-to-no discernible breakage or shedding.

Table 92-1 Differential Diagnosis of Alopecias

[edit] Scarring Alopecias

[edit] Tinea Capitis.

For etiology, epidemiology, and management, see Chapter 91 .

[edit] History and Physical Examination.

Tinea capitis may present either as hair breakage, accompanied by minor scaling, or as tender, boggy patches of alopecia (kerion). Symptoms range from none, to pruritus, pain, and tenderness.

[edit] Management.

Usually systemic antifungal agents are required to treat tinea capitis. Combined use of systemic antifungal therapy and systemic corticosteroids are necessary to treat kerions (see Chapter 91 ).

[edit] Discoid Lupus Erythematosus.

For etiology/epidemiology, pathophysiology, and management, see Chapter 135 .

[edit] Physical Examination.

Discoid lupus erythematosus presents as patches of hair loss with scarring throughout the affected area, hyperpigmentation and hypopigmentation, telangiectasias, and follicular hyperkeratosis.

[edit] Differential Diagnosis.

See Table 92-1.

[edit] Management.

Therapy of inflammatory scarring alopecias may include topical, intralesional or oral corticosteroids, topical or oral antibiotics, topical or oral antifungal medications, and in selected, severe cases, antimalarial drugs or dapsone (see Table 92-1).

[edit] Nonscarring Alopecias

[edit] Hair Shaft Disorders

[edit] Shedding Because of Breaking Hair Shafts.

Structural hair shaft abnormalities can be acquired or congenital. Acquired forms are from breakage due to improper or too frequent use of chemicals for permanent waving, straightening, dying, or bleaching. Cessation of the offending cosmetic processing usually results in normal regrowth.

The major groups of congenital hair shaft abnormalities include fractures, irregularities, or twisting and coiling of the hair shafts. They may be seen as an isolated finding or be associated with abnormalities of nails, teeth, and sweat glands. A full discussion of these disorders is beyond the scope of this chapter. Microscopic examination of the hair under light magnification is usually sufficient for diagnosis by a sophisticated observer.

[edit] Trichotillomania.

Trichotillomania is an abnormal compulsion to pull out one's own hair (Fig. 92-1).

Figure 92-1 Trichotillomania. Note large area of incomplete hair loss.

[edit] Etiology/epidemiology.

There are two types of trichotillomania. The first, which occurs in those less than 6 years, is usually self-limited, and is more common in boys. The second type begins in those over 6 years and females are affected ten times more often than males. This type has a chronic course. Scalp hair pulling predominates, but any site may be affected.

[edit] History.

Although the cause is pulling of one's hair, frequently the patient does not admit to pulling and parents are not aware of the habit.

[edit] Physical examination.

Clinically, trichotillomania presents as irregular, bizarre shapes of hair loss with stubble of different lengths, distorted hair tips from manipulation, and often retained bits of hair at scalp level, which appear as black dots.

[edit] Laboratory evaluation.

In those patients who deny pulling their hair, a biopsy may be necessary. Pathognomonic histologic findings called trichomalacia (pigmented fragments of hair shafts within follicles) confirm the diagnosis.

[edit] Management.

Treatment is difficult. Behavior modification training is sometimes helpful as may be newer medications used for treating obsessive-compulsive disorders such as clomipramine and fluoxetine.

[edit] Anagen Arrest.

Anagen arrest refers to alopecia in patients receiving systemic chemotherapy or local irradiation. The insult to the matrix cells is severe enough to cause temporary cessation of mitosis of matrix cells in anagen phase, with a resultant breakage of the hair shafts below scalp level. Hairs are shed 2 to 3 weeks after treatment. Because about 90% of scalp hairs are in anagen phase at any given time, the resultant hair loss can be almost complete. Chemotherapy is

generally not scarring so that hair regrowth begins when treatments are stopped. Attempts at prevention include ice-filled “chemo-caps” to reduce circulation to the scalp during therapy.

[edit] Shedding with Roots Attached.

See Table 92-1.

[edit] Telogen Arrest (Effluvium)

[edit] Pathophysiology.

Telogen arrest is caused by insults to the growing hairs that are sufficient to cause a greater than usual number of anagen hairs to cycle prematurely into the resting or telogen phase. After 30 to 90 days in telogen phase, the hairs are shed. Daily hair counts exceed 100 a day. Acute and chronic causes exist (Box 92-2), and many drugs can cause this form of shedding (Box 92-3).

[edit] History.

See Box 92-1.

[edit] Management.

Treatment includes identification and elimination of any offending causes. It is usually self-limited and reversible.

[edit] Alopecia Areata.

Translated literally, alopecia areata means patchy hair loss. However, the disease can be extensive resulting in loss of hair over the entire scalp (alopecia totalis) or over the entire body (alopecia universalis).

[edit] Etiology/epidemiology.

Alopecia areata is a common cause of hair loss and can occur at any age. The peak incidence is between 20 and 50 years, and sex distribution is equal.

[edit] Pathophysiology.

Alopecia areata is thought to be autoimmune in nature. The precise mechanism is not known.

[edit] History.

The most common presentation is the sudden appearance of asymptomatic, round patches of complete hair loss, usually limited to the scalp, although any hair may be affected. In the most severe cases, rapid hair loss with extensive total scalp hair shedding can be seen.

[edit] Physical examination.

Round patches of smooth alopecia with no inflammation are the usual finding ( Plate 84 ). “Exclamation-point” hairs (short broken-off hairs) may be present around the perimeter of the patches. Loss may be either limited to an occasional inconspicuous spot or total or universal (Fig. 92-2).

Figure 92-2 Alopecia areata (alopecia totalis). Note completely smooth scalp where hair has fallen out.

[edit] Laboratory evaluation.

Usually, laboratory evaluation is not required. In atypical cases, a skin biopsy can be helpful. In rare cases, there are coexistent autoimmune associations, including thyroid disease, vitiligo, diabetes mellitus, Addison's disease, pernicious anemia, and connective tissue disease. Laboratory evaluation to exclude these diseases should be based on suggestive history.

[edit] Differential diagnosis.

Tinea capitis and scarring alopecias, such as folliculitis decalvans, should be considered.

[edit] Disease course.

In general the disease is more extensive and chronic in childhood, with a poorer prognosis for spontaneous, permanent regrowth. The vast majority of adults with alopecia areata experience the intermittent occurrence of asymptomatic bare patches with spontaneous regrowth.

[edit] Management.

No treatments are predictably effective, especially in extensive hair loss. Treatments include immune suppressants, such as UV light, potent topical corticosteroids, intralesional corticosteroids (betamethasone 6 mg/ml or triamcinolone 3 to 10 mg/ml given monthly), and rarely oral corticosteroids. Immune stimulation through irritant or allergenic compounds (squaric acid, anthralin) applied to the affected areas, and direct hair growth stimulation with topical minoxidil also can be effective. In cases of extensive hair loss, a well-styled wig is sometimes the best alternative. Oral corticosteroids should be used for limited periods of time, 3 to 6 months maximum. Intralesional corticosteroids are injected in small increments into the bare patches with a dosage totalling no more than 20 to 30 mg/month over the long term.

[edit] Androgenetic Alopecia

[edit] Etiology/epidemiology.

Androgenetic alopecia, or malepattern balding, affects up to about 50% of men.^[2] Androgenetic alopecia can be present in as many as 37% of postmenopausal women. Asians appear to be less susceptible than whites or blacks. The genetic predisposition appears to be multifactorial rather than of a single maternal gene as was previously thought.

[edit] Pathophysiology.

The metabolism of androgens within hair follicles and a genetic predisposition are the requirements for the development of androgenetic alopecia. The activity of the enzyme 5-α-reductase in the scalp, which converts testosterone to dihydrotestosterone (DHT), appears to play a role in the process of hair miniaturization. Serum levels of circulating androgens are not elevated in most cases. In both men and women there is a progressive shortening of the anagen phase, which leads to smaller, finer hairs with each succeeding cycle.

[edit] History.

Gradual thinning of the scalp hair is typical. A history suggestive of masculinization requires evaluation for possible systemic androgen excess.

[edit] Physical examination.

In men the usual pattern is temporal recession and thinning on the vertex with gradual progression to total balding of the frontal and vertex scalp. In women the thinning is more diffuse over the crown and usually spares the frontal scalp line and temporal areas. In both men and women, the parietal and occipital scalp are not involved.

[edit] Laboratory evaluation.

In men the diagnosis is usually apparent. In women occasionally there can be uncertainty. In these cases, certain laboratory tests to exclude causes of telogen effluvium (see the box at top left) plus a scalp biopsy can be helpful.

[edit] Management.

The only treatments currently available are the topical use of minoxidil (2% and 5%) in men and women and oral finasteride in men and surgical hair transplantation. Ongoing research in the use of androgen antagonists may possibly result in effective treatments.

[edit] NAIL DISEASES

Nail disorders (Table 92-2) are common complaints among patients. The physician treating nail disorders must have a thorough understanding of the anatomy of the nail and its growth pattern.^[3][4][5]

Table 92-2 Differential Diagnosis of Nail Disorders

[edit] Anatomy and Terminology

The nail plate is surrounded by folds on three sides: the two lateral nail folds and the proximal nail fold. The nail folds are collectively the parionychium. The area beneath the free edge of the nail, the hyponychium, is contiguous with the volar skin of the digit. The nail bed lies beneath the nail plate and contains the blood vessels and nerves. The nail matrix is the root of the nail, and its distal portion is visible on some nails as the half-moon shaped structure called the lunula.

[edit] Nail Growth and Kinetics

Nails grow at a rate of approximately 0.1 mm/day, which means it takes about 4 to 6 months to regenerate a fingernail and 8 to 12 months to replace a toenail. The nail matrix is the germinative portion of the nail and is responsible for the formation of the nail plate. Damage to the matrix usually results in an abnormal nail plate, which may result in a permanent nail dystrophy such as a split nail. Conversely, an injury to the nail plate or nail bed will usually allow for regrowth of a normal nail.

[edit] Infectious Nail Diseases

[edit] Onychomycosis (Fungal Nail Infection).

Approximately 50% of all nail disorders are fungal in origin. Fungal infections of the nails are common worldwide without racial predilection. Some persons may have genetic predisposition to the development of chronic tinea unguium. Other factors that may increase the development of onychomycosis are humidity, heat, trauma, diabetes mellitus, and underlying tinea pedis.

[edit] Tinea Unguium.

The most common type of onychomycosis, tinea unguium, is caused by a dermatophyte fungus. Nonfungal nail conditions, such as psoriasis, can be indistinguishable from onychomycosis; therefore it is important not to rely on clinical inspection alone to diagnose fungal infections of the nail. A potassium hydroxide (KOH) preparation or fungal culture should be performed to substantiate the diagnosis. An adequate culture requires obtaining subungual debris at least 1 or 2 mm under the nail.

[edit] Physical Examination.

The various subtypes of tinea unguium are based on their pattern of involvement of the nail unit.

Superficial white onychomycosis (Fig. 92-3) is characterized by white discoloration on the surface of the patient's nail, which can be easily scraped away with a blade. It occurs only on the patient's toenails and is easily treated with any of the topical antifungal medications. The causative organism is Trichophyton mentagrophytes in most of the cases.

Figure 92-3 Superficial white onychomycosis.

Distal subungual onychomycosis (DSO) (Fig. 92-4) is so named because the site of invasion is the distal nail bed and progression is distal to proximal. Nail bed hyperkeratosis and yellow brown discoloration is usually present, with eventual crumbling and disintegration of the nail plate. The most common dermatophytes are T. rubrum and T. mentagrophytes, although others also can be seen. DSO of the toenails is usually associated with tinea pedis. When it occurs in fingernails, it is often associated with scaling of the palm of the affected hand and both feet. The organism on the hands is usually T. rubrum.

Figure 92-4 Distal subungual onychomycosis.

Proximal subungual onychomycosis (PSO) occurs when the organisms invade the nail plate proximally from the proximal nail fold and involves the ventral nail plate. The clinical presentation is a white or yellow discoloration on the inferior surface of the nail plate extending out from the proximal nail fold. The causative organisms of this rare form are T. rubrum, T. mentagrophytes, T. schoenleinii, and T. tonsurans. In patients infected with human immunodeficiency virus, a variant called proximal white subungual onychomycosis (PWSO) is seen in which the nail is white proximally and with a superficial, as well as deep, involvement.

[edit] Differential Diagnosis.

Psoriasis is the most common nail disorder that can be mistaken for tinea unguium. Usually other signs of psoriasis are present on the body. In certain cases, confirmation by KOH examination of nail debris and fungal culture for identification are required.

[edit] Management.

Treatment of onychomycosis must be tailored to the type of infection and the individual patient's needs. Because onychomycosis is often overdiagnosed, it is important to demonstrate fungus by KOH or culture before initiating oral antifungal therapy. There are currently three medications approved for the indication of onychomycosis: griseofulvin, itraconazole, and terbinafine. The latter two drugs have become widely used for this condition because of shortened treatment times and increased efficacy. See Table 91-1 for a comparison of these antifungal drugs.

Itraconazole (Sporanox) is a triazole antifungal that is fungistatic and has activity against dermatophytes, yeasts, and some molds. It is used continuously at a dose of 200 mg daily for 90 days or preferably in a pulse dose of 200 twice a day for 1 week per month for 2 months for fingernails and 3 months for toenails. When used in a pulse dose schedule, laboratory monitoring is optional.

Terbinafine (Lamisil) is an allylamine drug that is fungicidal. Its coverage is excellent for dermatophytes but is less active against yeasts and molds. The usual dose of terbinafine for toenail fungus is 250 mg daily for 90 days. Terbinafine remains in the nail plate for at least 3 months after discontinuing therapy. It has few drug-drug interactions and periodic laboratory monitoring is recommended.

Another newer oral antifungal drug with clinical usefulness in onychomycosis is fluconazole (Diflucan). This drug does not have FDA approval for the indication of onychomycosis; however, studies show that it has good efficacy and safety for nail fungus. It is given in a dose of 200 to 300 mg once weekly for the length of time it takes for the nail to become clinically normal (6 to 12 months). It is fungistatic and covers yeast, dermatophytes, and some molds.

[edit] Paronychia.

Paronychia is defined by infection or inflammation of the nail folds. It can be acute or chronic based on the pathogenesis and organism.

[edit] Acute Paronychia.

Acute paronychia results from a bacterial infection of the nail folds. It usually follows some kind of trauma to the nail folds such as overly aggressive manicuring or injury. The most common bacterial agents in acute paronychia are Staphylococcus aureus and Pseudomonas species. Treatment is similar to treatment of other bacterial infections of the skin and includes draining and administering culture-specific antibiotics.

[edit] Chronic Paronychia.

Chronic paronychia causes swollen, red, tender, boggy nail folds. It occurs most frequently in people with wet work jobs or those whose hands are exposed to solvents and chemicals. The first occurrence is separation of the cuticle and nail folds from the nail plate, followed by the formation of a potential space for various microbes to invade, especially C. albicans.

[edit] Management.

Treatment includes drying the area and applying anticandidal agents. In cases of severe paronychial inflammation, topical or intralesional steroids can be used. It is important to educate the patient about excessive water and chemical exposure.

[edit] DERMATOLOGIC DISEASES THAT AFFECT THE NAILS

[edit] Psoriasis

Psoriasis occurs in 2% to 3% of the population, and between 10% and 50% of psoriatics have nail involvement (see Chapter 85 ).

[edit] Physical Examination.

Psoriasis of the nails can have a variety of clinical manifestations depending on the site of the involved nail unit. Nail pitting (in the nail plate) is due to involvement of the matrix; onycholysis, subungual hyperkeratosis, and yellow discoloration (“oil drop sign”) are due to involvement of the nail bed. Psoriasis of the nail is often indistinguishable clinically from fungal infection of the nail (see Plate 28 ). Clinical inspection of other areas of the body that are prone to psoriasis (elbows, knees, scalp, gluteal cleft) and negative KOH examination and fungus culture can provide clues to the diagnosis of psoriasis of the nails. Approximately 5% of patients with psoriasis have psoriasis limited to the nails, a situation that poses a great diagnostic challenge.

[edit] Management.

Treatment of psoriasis of the nails can be challenging. Often as cutaneous psoriasis clears, the nails clear as well. Topical steroids in a liquid or gel form may be helpful in some mild cases; however, results are usually disappointing in severe psoriatic involvement of the nails. Intralesional steroids (triamcinolone 3 mg/ml) injected into the nail fold overlying the matrix are generally more helpful, although not always welcomed by the patient. Psoralen plus UV A (PUVA) and grenz ray are sometimes beneficial in severe cases. A dermatologist should be consulted for these treatments.

[edit] Lichen Planus

Lichen planus is a relatively uncommon disorder that can affect the skin and/or nails (see Chapter 85 ). When it occurs in the nails, it can rapidly destroy the nail matrix, leading to onychorrhexis (longitudinal ridges) and occasionally eventual destruction of the nail plate. The end stage of lichen planus of the nails is destruction of the matrix so that portions of the nail fail to grow. The resultant defect is called a pterygium and is characterized by areas of the nail where the proximal nail fold adheres to the nail bed where the nail is absent.

[edit] Management.

Potent topical corticosteroids can be tried, but systemic steroids are sometimes necessary for the treatment of rapidly destructive lichen planus of the nails.

[edit] Neoplastic Nail Conditions

[edit] Malignant Melanoma.

Malignant melanoma of the nail unit is rare, accounting for only 1% to 4% of melanomas. Although 20% of these are amelanotic (containing little or no pigment), most start as a solitary longitudinal pigmented band in the nail. The band usually widens and darkens over time and frequently there is leaching of pigment into the proximal nail fold (Hutchinson's sign). The most commonly involved nails are the great toe and thumb. Over 25% of patients give a history of prior trauma to the digit, which in some cases causes delay in seeking medical attention. There are many benign causes of longitudinal pigmented bands in the nail ranging from hematoma and certain medications to a normal occurrence in blacks; but any solitary pigmented band that widens, darkens, or otherwise alters the nail plate needs further evaluation. The onus is on the physician to be certain that a pigmented band or spot on the nail is not a melanoma.

[edit] Management.

Early detection and wide surgical excision are essential. When there is doubt about the diagnosis, referral to a dermatologist and biopsy of nail bed, nail matrix, or surrounding tissue are indicated. Once the diagnosis of malignant melanoma is confirmed, referral to an oncologic surgeon experienced in the management of malignant melanoma is mandatory (see Chapter 87 ).

Other cutaneous neoplasms occasionally are seen in the nail unit. Both basal cell carcinoma and squamous cell carcinoma occur rarely in the nail bed. A benign painful tumor that is often seen in a subungual location is a glomus tumor, an encapsulated tumor of the arteriovenous anastomosis in the nail bed. These tumors may be seen beneath the nail as a red or blue discoloration, but the main distinguishing feature is pain, which may be spontaneous or associated with cold. A benign bony growth called an exostosis can occur subungually, usually beneath the toenail, and often after trauma to the digit.

[edit] Other Common Nail Disorders

[edit] Habit Tic Disorder.

Habit tic disorder ( Plate 85 ) is a common disorder that is self-induced and characterized by horizontal parallel ridges in the nail plate. It results from frequent repetitive manipulation of the cuticle and nail fold overlying the matrix. The thumb is the most commonly involved digit. Once the cause of the problem is explained to the patient, the cure is simply a matter of leaving the nail alone.

[edit] Digital Mucous Cyst.

Mucous cysts are the most common tumor of the digit and usually occur on the dorsal surface of the finger between the nail folds and the distal interphalangeal joint. They are not a true cyst because they lack a cystic lining but are more accurately called focal mucinosis.

[edit] Nail Changes in Systemic Disease.

Some nail findings provide helpful clues for the diagnosis of systemic disorders. A few nail signs are specific for underlying medical problems. Nail fold telangiectases are associated with connective tissue disorders such as systemic lupus erythematosus and dermatomyositis. Clubbing is associated with pulmonary and gastrointestinal disorders. Other much less specific nail signs, such as splinter hemorrhages, may be seen in subacute bacterial endocarditis but are commonly seen in trauma (Table 92-3).

Table 92-3 Nail Signs of Systemic Disease

[edit] DISORDERS OF PIGMENTATION

Hyperpigmentation and hypopigmentation occur when a variety of things go wrong, including (1) changes in the number of melanocytes, (2) alterations in melanin synthesis, and (3) changes in hormonal balance. These alterations can be either congenital or genetic conditions or acquired diseases.

[edit] Hyperpigmentation

Generalized hyperpigmentation is usually caused by systemic conditions including endocrine, metabolic, and nutritional conditions. Addison's disease causes diffuse hyperpigmentation with accentuation in scars, palmar and plantar creases, and mucous membrane–pigmented patches. Secretion of cortisol from the adrenal glands suppresses melanocyte-stimulating hormone (MSH) and adrenocorticotrophic hormone (ACTH) release from the pituitary. Lack of cortisol with loss of adrenal gland function allows uninhibited release of MSH-stimulating melanocyte pigmentary synthesis. Glucocorticosteroid replacement slowly reverses the hyperpigmentation.

ACTH-and MSH-secreting tumors cause similar Addisonian pigmentation. Pregnancy and oral estrogen stimulate pigmentation of the nipples, areolae, and genitalia, as well as localized patches in the sun-exposed areas on the face ( Plate 86 ). Several metabolic diseases (porphyria cutanea tarda, advanced liver disease, hemochromatosis, and chronic renal failure) and nutritional diseases (kwashiorkor, pellagra, inflammatory bowel disease, and malabsorption) cause hyperpigmentation. Hemochromatosis gives an unusual bronze hyperpigmentation. Certain drugs also cause hyperpigmentation , including bleomycin, fluorouracil, and busulfan (see Chapter 99 ).

Several genetic and acquired conditions cause the following pigmented lesions:

Simple lentigo: Flat brown to black spots, 2 to 3 mm in diameter on the trunk and proximal extremities, due to an increase in melanocytes at the dermal-epidermal junction; they do not hyperpigment with UV light exposure.

Freckles (ephelides): Tan macules in sun-exposed areas that darken with sun exposure; they are the result of increased melanin synthesis within a normal number of melanocytes.

Solar lentigo: Brown flat lesions on sun-exposed areas due to increased numbers of melanocytes; these lesions increase in numbers in individuals over 40.

Various nevi: Including mongolian spots ( Plate 87 )—blue-black pigmentation in sacrogluteal region present at birth; nevus spilus—light brown patch with speckled dark, brown macules within ( Plate 88 ).

Miscellaneous localized pigmented lesions in inherited conditions: Café au lait macules in neurofibromatosis. Brown to black macules on the lips and buccal mucosa in Peutz-Jeghers syndrome. Associated polyposis of the large and small intestine are a prominent part of this condition. Incontinentia pigmenti in an X-linked dominant disease with streaks and whorls of hyperpigmentation following the lines of Blaschko^[6] that is seen in females and associated with ophthalmologic, bony, and CNS abnormalities.

Postinflammatory hyperpigmentation: Common in dark-skinned individuals; occurs after any inflammatory process including acne, folliculitis, minor injuries, and numerous other skin disorders.

[edit] Management.

Replacing cortisone in Addison's disease will result in slow resolution of the hyperpigmentation. Hyperpigmentation of a variety of types can be improved using creams containing hydroquinone (3% to 4%) applied twice a day in conjunction with avoidance of sun and the use of sunscreen. Hydroquinone suppresses pigmentation by interfering with tyrosinase activity.

[edit] Hypopigmentation

Generalized loss of pigment is usually the result of oculocutaneous albinism, a group of genetic diseases that are associated with light hair color, nystagmus, and poor visual acuity.

[edit] Localized Hypopigmentation.

Vitiligo ( Plate 89 ) is a condition in which melanocytes are destroyed, possibly on an immunologic basis, resulting in symmetric or segmental white macules. Common areas of involvement include perioral, periocular, genital areas, and hands. Spontaneous repigmentation occurs in some patients. Vitiligo may be seen in association with the autoimmune conditions, including Hashimoto's thyroiditis, diabetes mellitus, pernicious anemia, and Addison's disease.

Piebaldism or white forelock consists of depigmentation due to an absence of melanocytes over the forehead and frontal scalp, chest, mid arms, and thighs.

Waardenburg's syndrome is an inherited defect of neural crest–derived elements consisting of poliosis (white forelock), deafness, broad nasal root, epicanthic eyefolds, and heterochromia of the irides.

Tuberous sclerosis is a phakomatosis and one of the earliest signs is hypopigmented macules present at birth. Typically, these macules are “ash leaf” in shape but may be polygonal. Wood's lamp examination of skin accentuates these areas of depigmentation.

Chemically induced depigmentation is caused by exposure to rubber products, germicidal agents, and industrial cleaning solutions. This exposure can cause irregular depigmented areas simulating vitiligo. These chemicals contain phenols and hydroquinones that destroy melanocytes.

[edit] Treatment of Hypopigmentation Conditions.

Vitiligo is difficult to treat. Sunscreens are necessary to prevent burning. PUVA therapy has had limited success. Patients should be referred to a dermatologist for PUVA therapy. Chemically induced depigmentation also may benefit from PUVA therapy. If the vitiligo is extensive, depigmentation of the remaining normally pigmented skin may be a reasonable option. This procedure should also be supervised by a dermatologist.

[edit] REFERENCES