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Chapter 28 • Rashes and Skin Lesions
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329
Table 28-2
Descriptive Dermatological Terms—cont’d
LESION* CHARACTERISTICS EXAMPLES
Universal zosteriform† Entire body involved
Linear arrangement along
nerve distribution
From Swartz MH: Textbook of physical diagnosis: History and examination, ed. 6, Philadelphia, 2009, Saunders.
*Examples of different configurations of skin lesions and their descriptions are contained within Table 28-1.
†Also known as dermatomal.
Macule
Papule
Alopecia universalis;
herpes zoster
Plaque
Wheal
Bulla
FIGURE 28-1 Types of skin lesions. (From, Ball JW, Dains JE, Flynn J, et al: Seidel’s guide to physical
examination, ed. 8, St. Louis, 2015, Elsevier.)
Nodule
Pustule
Vesicle
Cyst
Continued
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Chapter 28 • Rashes and Skin Lesions
Scale
FIGURE 28-1, cont’d Types of skin lesions. (From, Ball JW, Dains JE, Flynn J, et al: Seidel’s guide to physical
examination, ed. 8, St. Louis, 2015, Elsevier.)
Excoriation
AtropyCrustUlcer
Fissure
A
FIGURE 28-2 Typical distribution of papulosquamous eruptions in children. A, Atopic dermatitis: usually
located on cheeks, creases of elbows, and knees. B, Seborrheic dermatitis: usually located on scalp, behind ears, in thigh creases, and in eyebrows. C, Scabies: usually located on axillae, webs of fingers and
toes, and intragluteal area. (From Berkowitz C: Pediatrics: A primary care approach, ed. 2, Philadelphia,
2000, Saunders.)
B
C
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Fever
Fever is common in viral exanthems (rashes), and the
accompanying condition is usually not life-threatening.
However, fever, irritability, hypotension, and a macular
or petechial rash may indicate meningococcemia. Treatment needs to be immediate to be lifesaving.
Allergic Reaction
Urticarial allergic reactions may be associated with
angioedema (swelling) of the extremities, face, lips,
tongue, and/or airway. Other symptoms include cough,
wheezing, shortness of breath, and heart palpitations.
The sooner symptoms occur after the exposure to the
allergen, the more severe the reaction will be. Treatment needs to be instituted immediately.
Rash With Mucosal Involvement
Toxic epidermal necrolysis (TEN), and StevensJohnson syndrome are severe mucocutaneous reactions, most often to medications, characterized by
extensive necrosis, and epidermis detachment. These
conditions are considered variants of a continuum,
based on the percentage of body surface involved.
TEN is a more severe condition involving more
than 30% of the body surface. Reactions include
a tender, morbilliform, erythematous rash accompanied by fever, conjunctivitis, oral ulcers, and diarrhea. Immediate hospitalization is required to treat
exfoliation of large areas of skin.
Box 28-1
ACUTE CHRONIC
• Allergic or contact
dermatitis
• Candida dermatitis
(diaper rash, intertrigo)
• Erythema infectiosum
(fifth disease)
• Erythema multiforme
• Fixed drug eruptions
• Folliculitis
• Herpes simplex virus
(HSV)*
• Herpes zoster/varicella
zoster (HZ)
• Impetigo
• Infestations (scabies,
pediculosis)
• Insect bites
• Kawasaki disease
• Pityriasis rosea
• Septicemia
(meningococcal)
• Scarlet fever
• Tinea (corporis, pedis,
versicolor)
• Urticaria*
• Viral exanthems (measles)
Where is the rash in its evolution?
Duration of Rash
• Acne vulgaris
• Bullous pemphigus
• Eczema
• Erythema nodosum
• Kaposi sarcoma
• Mycosis fungoides
• Polyarteritis nodosa
• Psoriasis
• Rosacea
• Seborrheic dermatitis
• Systemic lupus
erythematosus
Is the rash acute or chronic (recurrent)?
Key Questions
l
How long have you had this rash?
l
Have you ever had a rash like this before?
Onset
The diagnosis of skin lesions is initially aided by
categorizing the lesion as acute, chronic, or recurrent.
Acute eruptions, such as urticaria or various fungal
rashes (tinea), are classied as such because they have
a tendency to be self-limiting with no recurrence after
effective treatment. Chronic rashes, such as psoriasis
or eczema, may persist or be recurrent with exacerbations and remissions. Box 28-1 shows common rashes
categorized by duration. Ascertain the duration of the
eruption when symptoms are described by the patient;
however, the initial occurrence of a chronic rash may
be an acute presenting symptom. Conversely, an acute
eruption not optimally treated may become a chronic
problem.
Key Questions
l
What did this look like initially?
l
Has the rash changed? If so, how?
l
Has it spread? Where?
Initial Presentation
Most skin lesions evolve over time, although this varies from minutes with urticaria, to weeks or even
months with psoriasis or cutaneous T-cell lymphoma.
Change in Lesion
Determining whether there has been a change from the
initial appearance of a lesion provides diagnostic clues.
The eruption of pityriasis rosea classically begins with
a “herald patch,” a single, scaly, erythematous patch
usually on the trunk, followed within days by a
regional outbreak of numerous smaller erythematous
patches, thus providing a key diagnostic clue. The rash
may look like that of ringworm, but it appears too
quickly to be ringworm. Another example of evolutionary change is the eruption of herpes simplex virus
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Chapter 28 • Rashes and Skin Lesions
(HSV), which begins with a prodrome of burning, tingling, or itching, followed by the development of small
vesicles that later umbilicate, possibly ooze, and eventually crust before healing. A rash may appear in different ways, depending on the point at which evaluation
is sought.
Spread
The way in which a rash spreads is helpful in diagnosing the specic rash. There are three general ways in
which a rash can spread: centripetal, or moving to the
center; centrifugal, or moving away from the center;
and caudal, or moving down.
What does the presence of pruritus tell me?
Key Question
l
Does it itch?
Itching
All dermatoses can be classied into three groups:
a small group that always itches, those that never itch,
and an intermediate group in which itching is variable
(Box 28-2). Pruritus is often reported to be worse
at night; during the day, pruritus is less troublesome
because the patient is distracted by daily routines. At
bedtime the slightest sensation of pruritus may become
overwhelming because the patient is focusing on trying
to sleep. Once the patient scratches the area, histamine
is released from the inammatory cells (especially
mast cells) and this causes more pruritus, and an itch/
scratch cycle is established.
Swimmer’s itch, also called cercarial dermatitis,
occurs in areas unprotected by a swimsuit. It is an
allergic reaction to a microscopic parasite that burrows
under the skin. Seabather’s itch occurs in areas under
the swimsuit. Nocturnal pruritus most typically occurs
in scabies infestations. Itching in the absence of a rash
may be an important clue to internal disease.
What does associated pain tell me?
Key Questions
l
Is it painful or sore?
l
Does it burn?
Pain
Pain is a rare symptom with skin rashes. Skin lesions
that ulcerate or are associated with swelling can be
painful. The classic painful rash is associated with
herpes zoster (HZ), including postherpetic neuralgia.
Severe psoriasis or eczema with ssures and bleeding
may also be described as painful by some patients.
Soreness is a more common symptom and is associated
with numerous rashes. Tender erythema may be associated with toxic epidermal necrolysis.
Burning
Burning is infrequently reported. It is most notable preceding the rash in herpes virus infections (e.g., HSV or HZ).
What do associated symptoms tell me?
Key Questions
l
Do you have a fever? Sore throat? Headache?
l
How are you feeling in general?
Fever, Sore Throat, and Headache
Fever is a common presenting complaint in infectious
diseases accompanied by rash, such as HZ, erythema
infectiosum, scarlet fever, endocarditis, or Kawasaki
disease. Malaise, sore throat, nausea, or vomiting can
occur with mononucleosis.
General Health
In a patient with a maculopapular eruption, the two
most common causes are drug reaction and viral illness. Inquire about viral symptoms, such as fever,
malaise, and upper respiratory tract or gastrointestinal
symptoms.
Box 28-2
ALWAYS ITCH MAY ITCH NEVER ITCH
• Atopic dermatitis
• Urticaria
• Insect bites
• Scabies
• Pediculosis
• Lichen planus
• Chickenpox
Itching Comparison
• Psoriasis
• Impetigo
• Tinea
• Pityriasis
rosea
• Warts
• Neurofibromatosis
• Vitiligo
• Nevi
Are there possible contacts or sources of contagion?
Key Questions
l
Does anyone with whom you live or have close con-
tact have something similar? If so, how long have
they had it?
l
Have you traveled recently? Where?
l
What do you do for a living? What are your hobbies
or leisure activities?
l
Do you have any pets? Have you been around animals?
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Living Situation
Explore the patient’s living situation. The geographic
details of his or her daily activities may help provide
diagnostic clues, particularly for rashes caused by
infectious or infestation mechanisms. Children, in
particular, may contract scabies, pediculosis (lice), or
impetigo by direct contact in school or daycare.
Travel
A patient may develop a rash weeks or months after
travel exposure. Diseases endemic to other parts of the
world may have presenting symptoms of rash, including erythema nodosum, which is common in Southeast
Asia, or leprosy, which is common in many parts of the
world, especially in tropical and subtropical climates.
Both eruptions may also occur secondary to tuberculosis. About 40% of erythema nodosum is idiopathic and
can be related to inammatory disease and malignancy.
Leishmaniasis is a parasitic infection spread by the bite
of phlebotomine sand ies. It is seen in the tropics,
subtropics, and southern Europe. Camping trips to
wooded areas, especially in the Eastern and upper Midwestern United States, may result in a bite by a deer
tick, causing Lyme disease, the leading vector-borne
infectious disease. The resultant skin eruption in Lyme
disease is known as erythema chronicum migrans
(ECM), which begins 4 to 20 days after the bite of the
tick; only a third of patients remember being bitten.
Rocky Mountain spotted fever (Rickettsia rickettsii) is
transmitted by a tick bite and is common in the south
Atlantic region of the United States. Initial symptoms
are nonspecic; later symptoms are a petechial rash
and fever, usually requiring hospitalization.
Other Exposures
Outdoor occupations or leisure activities may expose
individuals to a variety of sources for rashes and
lesions, including insect bites as well as allergic or
contact dermatitis from poison ivy and chemical substances. People exposed to animal skins contaminated
with Bacillus anthracis may develop cutaneous anthrax, which is characterized by lesions that evolve
from a papule through a vesicular stage to a depressed
eschar. Sun exposure can also worsen chronic eruptions such as rosacea or the malar buttery rash in
systemic lupus erythematosus (SLE). Ringworm is
common in farmers and ranchers who work with cattle.
Pets
Flea bites produce an urticarial lesion with a central
punctum. The reaction is an immunological one, making it different in each individual. Bites are usually on
the legs; infants may have bites on the arms or trunk.
New lesions may appear daily, and itching is variable
but sometimes intense. Fleas on a cat or dog are
usually the culprits. An atypical form of scabies can be
transmitted from dogs to humans; the presenting
symptom is usually a single lesion in an area under
occlusion and it lasts about 1 to 2 weeks.
Is there anything that exacerbates or triggers the
reaction?
Key Questions
l
Does anything seem to make this worse?
l
Do you have any known allergies?
Triggers
Patients often easily identify aggravating factors. Any
rash involving vasodilation will become more vivid and
likely more pruritic with heat exposure, whether via
sunlight, sweating, or a hot shower. Localized eruptions,
especially on the hands or forearms, prompt many patients to consider chemicals or other products as causes.
People with eczema whose hands are frequently
exposed to water are vulnerable to the development of
EVIDENCE-BASED PRACTICE
of Melanoma?
This review summarizes findings from 17 systematic reviews
and 2 guidelines on skin cancer between April 2008 and
2009. Melanoma primary-prevention measures, such as education, are more likely to be successful in younger children
than adolescents. The evidence does not currently support
Data from Macbe th AE, Grindlay DJ, Williams HC: What’s new in skin cancer? An analysis of guidelines and systematic reviews publi shed in
2008–2009. Clin Exp Dermatol. 36:453, 2011.
What is the Evidence About the Prevention and Diagnosis
population screening for melanoma by whole-body examination. Sunburn later in life increases the risk of melanoma as
much as sunburn early in life. Superior diagnostic accuracy
of dermoscopy over naked-eye examination for melanoma was
mixed.
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Chapter 28 • Rashes and Skin Lesions
irritant eczema on the exposed skin. Some foods occasionally exacerbate skin lesions. Rosacea is a vasomotor
instability disorder characterized by exacerbation with
dietary consumption of vasodilators such as coffee, tea,
alcohol, or spicy foods. Stress, whether physiological
(e.g., menstruation, pregnancy) or psychological, is
widely believed to trigger or worsen many chronic
rashes, especially eczema, acne, and psoriasis. Stress
also may facilitate recurrent eruptions of HSV.
Could this rash be caused by a medication?
Key Questions
l
Are you taking any medications (prescription or
over-the-counter medications)?
l
Do you have any medication allergies?
l
Have you had a recent vaccination?
Medication
There are four types of dermatological side effects of
drugs: light sensitivity (e.g., photodermatitis), allergic
reactions (e.g., urticaria, xed drug eruptions, morbilliform eruptions), commensal skin eruptions (e.g.,
pityriasis versicolor in a patient on systemic corticosteroids), and worsening of existing skin eruptions
(e.g., tinea eruptions mistakenly treated as eczema
with topical corticosteroids). Medications used after
the onset of a rash may be irritants or sensitizers and
worsen the condition.
Recent Vaccination
Infants and children who have recently had a measles
vaccination may display a rash 10 to 14 days after
immunization.
Is there a signicant dermatological family history?
Key Question
l
Does anyone in your family have chronic skin
problems?
Family History
A family history of dermatological problems may add
insight to the diagnosis. Atopic disease (eczema, asthma,
hay fever) tends to cluster in families. Psoriasis, seborrheic dermatitis, and rosacea are also frequently noted to
have a familial inheritance pattern. Multiple café-au-lait
spots with a positive family history for neurobromatosis can help identify children with this autosomal
dominantly inherited disease.
DIAGNOSTIC REASONING: FOCUSED
PHYSICAL EXAMINATION
Look At All the Skin and Mucous Membranes
A “peephole” diagnosis should be avoided; the whole
organ should be examined. If the patient is not fully
undressed, relevant lesions could be missed. However,
it is useful to select one typical well-dened lesion to
describe in detail, followed by an orderly and sequential system of examination so that no areas of the body
are missed. The feet should always be examined in the
presence of hand dermatitis so that a hypersensitivity
reaction to a tinea infection or a concomitant hand
tinea will not be missed. Erythema in dark-skinned
people may be difcult to appreciate; it often is seen as
postinammatory hyperpigmentation.
Inspect for Distribution
Determine if the lesion is widespread or localized,
unilateral or bilateral, symmetrical or asymmetrical.
Symmetrical lesions commonly have internal causes
(e.g., eczema, psoriasis); asymmetrical lesions have
external causes (e.g., bacterial or fungal infections,
allergic contact eczema). Is the lesion predominantly
on the exor (as in atopic dermatitis) or extensor (as in
psoriasis) surfaces? A rash on the soles or palms occurs
with erythema multiforme, secondary syphilis, and
rickettsial infections. Determine if the distribution is
conned either to protected areas or to light-exposed
areas such as in collagen-vascular diseases, photosensitive reactions to drugs, and airborne contact dermatitis. Is the lesion predominantly centrifugal (affecting
the extremities), as seen in erythema multiforme,
Rocky Mountain spotted fever, and insect bites, or
centripetal (sparing the extremities and concentrated
on the trunk)? Intertriginous distribution (neck, axilla,
groin) is found in candidiasis, some inammatory
fungal infections, and some forms of psoriasis.
Inspect the Mouth
Drug eruptions from sulfonamides, penicillin, streptomycin, quinine, and atropine often have associated mucosal
erosions (enanthems) and crusts. Mucosal involvement is
common in hand and foot lesions (e.g., hand-foot-andmouth disease), herpes, and syphilis. Oral lesions occur in
lichen planus, autoimmune blistering diseases, and malignancies such as squamous cell carcinoma.
Inspect the Hair
In children, a triad of hair loss, scaling, and lymphadenopathy is diagnostic of tinea capitis. A high index of
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335
suspicion is warranted in inner city urban areas, where
the condition is common.
Evaluate for hair loss that is diffuse or localized and
compare areas such as the temporal and crown region
to the occiput. Psoriasis and seborrheic dermatitis may
present as scaling and desquamation. A hair pull test
will reveal any increased hairs shed with a gentle pull.
Palpate the Skin
Palpate skin lesions to assess for tenderness, texture
and consistency, rmness, uctuance, and depth.
Smooth skin has no irregularity. Uneven skin has ne
scaling or some warty lesions. Rough skin feels like
sandpaper and is characteristic of keratin/horn or
crusts. Assessing the supercial skin for texture is done
by palpation with the ngertips. Deeper palpation is
done using the thumb and index ngers. Soft skin feels
like the lips, normal skin like the cheeks, rm skin like
the tip of the nose, and hard skin like the forehead. The
depth of the lesion determines if it is on the surface
or located within the dermis or subcutaneous tissue.
An indurated base is a thickening in the depths of the
lesion rather than on the surface.
Palpate the Regional Lymph Glands
Many viral exanthems will present with rash and
lymphadenopathy. Palpation of the regional lymph
glands may be of assistance in the diagnosis if neoplasm is suspected.
Perform an Abdominal Examination
The detection of hepatic or splenic enlargement
may assist in the diagnosis of a systemic cause of skin
disorders.
LABORATORY AND DIAGNOSTIC STUDIES
Diascopy
Diascopy is used to assess for blanching on pressure
and is accomplished by pressing a glass or clear plastic
slide on the lesion. Diascopy is most helpful in evaluating purpuric lesions; blood that is outside vessels (as in
petechiae) will not blanch, whereas blood that is entrapped within dilated vessels (as in telangiectasias)
will demonstrate this phenomenon.
Dermoscopy
Dermoscopy uses a skin surface microscope (dermatoscope) with or without the application of oil on a skin
lesion to illuminate and magnify a lesion. This technique allows a more detailed inspection of the surface
of pigmented skin lesions to conrm a diagnosis of
melanoma and to determine which skin lesions require
biopsy or removal. Dermoscopy requires special training and expertise.
Wood’s Light
Long-wave ultraviolet (UV) light is used in the diagnosis of lesions caused by fungal infections. Many but not
all fungal rashes uoresce different colors. Trichophy-
ton organisms and Tinea tonsurans, dermatophytes that
are frequently identied in tinea eruptions in the United
States, do not uoresce; Microsporum organisms,
which can cause tinea eruptions, do uoresce.
Skin Scraping and Potassium Hydroxide
Preparation
Microscopically examine a sample of cells retrieved
from a lesion, assessing for the presence of fungal or
dermatophytic spores and hyphae. The lesion should
be gently scraped using a scalpel (collect cells from an
active area such as the border of the lesion); the cells
are treated with a drop of 20% potassium hydroxide
(KOH) and then warmed or allowed to stand a few
minutes to soften the keratin. The addition of 40%
dimethyl sulfoxide (DMSO) to the KOH solution
accelerates diagnosis. Chlorazol black E stain highlights fungal hyphae as dark, blue-black against a light
gray background.
Tzanck Smear
In a Tzanck smear, an indirect test for herpes virus
infections (herpes simplex virus, herpes zoster), cells
are retrieved by swabbing the base of a lesion (usually a vesicle), smearing it onto a glass slide, and then
staining it with Giemsa or Wright solution. Examined
microscopically, the presence of multinucleated giant
cells conrms the presence of herpes virus, but
cannot differentiate between herpes simplex virus
or varicella-zoster virus infections. Viral culture is
diagnostic.
Bacterial or Viral Culture
For a bacterial culture, exudate from a lesion is
collected on a sterile swab and cultured for growth.
Gram staining may also be done. When a bacterial
isolate is known, antibiotic sensitivity testing is
performed.
For a viral culture, cells from the base of a lesion
(usually a vesicle) are collected on a Dacron swab
and cultured for identication of viral infections, particularly HSV or HZ.
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Chapter 28 • Rashes and Skin Lesions
Punch Biopsy
In a punch biopsy, a cylindrical-shaped tissue sample
is assessed histopathologically for identication. Select a punch size about 3 to 4 mm larger than the lesion
or sample an active area if the lesion is large. First the
skin is cleansed and local anesthesia is administered.
While stretching the skin with the other hand, gently
rotate the biopsy instrument while exerting slight
downward pressure. When well into the dermis,
remove the punch and excise the sample at its base.
The defect may be closed using electrocautery, with
suture(s), or left open to heal by second intention.
Place the fresh specimen on gauze with normal saline
for immediate transport to pathology to be processed.
If the specimen is being sent for culture or immunouorescent staining, place in a preservative such as
formaldehyde solution.
Excisional Biopsy
In excisional biopsy, a tissue sample is assessed histopathologically for identication. Excise the entire
lesion, usually making an elliptical incision around the
lesion beyond its margins. Excise the base and close
the defect with sutures or cauterize bleeding vessels.
Handle the specimen in the same manner used for a
punch biopsy.
DIFFERENTIAL DIAGNOSIS
The following conditions represent many of the most
common skin eruptions observed in primary care.
Follicular Eruptions
Acne Vulgaris
Acne presents as a chronic eruption of the pilosebaceous
unit, with noninammatory lesions (open or closed comedones) and/or inammatory lesions (e.g., papules, pustules, cysts), and is most commonly a problem of adolescents. Its distribution follows that of the sebaceous
glands: face, neck, chest, back, and upper arms. Neonatal
acne rst occurs between 2 and 4 weeks of age, lasting
until 4 to 6 months of age. Persistence beyond 12 months
may indicate endocrine dysfunction. African Americans
and other dark-skinned individuals need aggressive treatment to prevent postinammatory hyperpigmentation.
Rosacea
Rosacea is a vasomotor instability disorder characterized by sebaceous gland hypertrophy, papules, pustules, persistent erythema, and telangiectasias. It shows
a predilection for the face.
Infectious Eruptions
Impetigo
Impetigo presents as a supercial pustular, bullous, or
nonbullous eruption, followed by crusting (often honey
colored). The causative organism is usually staphylococci or streptococci. Contagion occurs via direct inoculation. It is typically a localized eruption that can
occur anywhere on the body, with a predilection for the
face and trunk.
Folliculitis
Folliculitis is a supercial pustular infection of the hair
follicles. Causative organisms are usually staphylococci
and occasionally streptococci or gram-negative organisms, including Pseudomonas, Klebsiella, and Proteus.
It is typically a localized eruption that can occur anywhere on the body, with a predilection for hairy areas
and exural regions.
Furuncle
A furuncle, often referred to as a boil, is a more
extensive infection secondary to folliculitis (see
Folliculitis).
Carbuncle
A carbuncle is an abscess of conjoined or adjacent
furuncles (see Furuncle).
Macular and Papular Eruptions
Erythema Infectiosum (Fifth Disease)
Fifth disease, also known as slapped cheek disease, is
a systemic illness of sudden onset characterized by
a coalescing, red, maculopapular eruption on the face.
A reticular eruption occurs on the extremities 2 to
3 days later. The causative organism is parvovirus B19.
This is a self-limiting condition.
Children with underlying hemolytic anemia may
experience an aplastic crisis.
Measles (Rubeola)
Measles are caused by a viral exanthem, and the systemic illness that results is characterized by a ne,
erythematous, morbilliform eruption on the face that
spreads to the trunk over 4 to 7 days, and becomes
conuent and reticulate. White patches on red mucosa (Koplik spots) appear on the buccal mucosa.
Cough, purulent coryza, photophobia, and fever
precede the rash. This is a self-limiting condition
and less common with widespread childhood immunization.
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Rubella
Rubella results from a viral exanthem similar to measles, starts as ne macules and papules on the face, and
progresses caudally within 24 hours. Lymphadenopathy
of postauricular nodes is characteristic of this disease.
Pityriasis Rosea
The presenting symptom of pityriasis rosea is a rapidly
evolving papulosquamous eruption of possible viral
etiology. An initial “herald patch” is characteristic, followed within days by numerous faintly erythematous
patches on the trunk and upper extremities (“T-shirt
and shorts” distribution). The lesions follow the lines
of cleavage and have a “Christmas tree” pattern on the
back. The patches demonstrate ne scaling, and mild
to severe pruritus may be present. It is more common
in the spring and fall and among adolescents. In African
American children, the eruption may consist only of
occasional oval lesions along the cleavage lines. The
remaining lesions are discrete, scattered follicular
or nonfollicular papules over the trunk and proximal
extremities. The face may also be involved.
Scarlet Fever
Scarlet fever is a systemic illness associated with
group A b-hemolytic streptococci (GABHS) (strep
throat) and is easily treatable with antibiotics. It is
characterized by a macular erythema of the face
(ushing), except around the mouth (circumoral pallor), followed by a disseminated ne papular erythema
(scarlatiniform), which may then desquamate. The
rash is intensied in the exor folds (Pastia lines).
Associated symptoms are sore throat, malaise, fever,
circumoral pallor, and a white or strawberry tongue.
Scarlet fever is a rarely occurring infectious disease in
the United States.
Roseola
Roseola is a viral infection caused by human herpesvirus 6 (HHV-6). It is characterized by 2 to 3 days of
sustained fever in an irritable infant who otherwise appears well. Mild edema of the eyelids and posterior
cervical lymphadenopathy are occasionally seen. After
the patient’s temperature decreases, a pink, morbilliform, cutaneous eruption appears transiently and fades
within 24 hours. This is a self-limiting condition.
Vesicular and Bullous Eruptions
Hand-Foot-and-Mouth Disease
Coxsackievirus A16 is the causative organism of this
viral exanthem and systemic illness. Painful mouth
ulcers followed by painful white vesicles with a surrounding erythema on the ngers, palms, toes, and
soles characterize the condition. Patients usually have
a low-grade fever, sore throat, and malaise for 1 to
2 days. Some develop submandibular or cervical
lymphadenopathy. This is a self-limiting condition.
Insect Bites
Mosquito and horsey bites can cause a common blistering reaction that is surrounded by faint erythema,
central pallor if swollen, and usually a visible central
punctum. The bites may be arranged in groups if they
are multiple. The lesions are pruritic and/or sore; the
condition is self-limiting. The deer tick bite causes a
bull’s-eye rash at the site of the bite.
Bed Bugs
The bed bug, Cimex lectularius, is a pest that feeds on
blood, causes itchy bites, and generally irritates their
human hosts. The Environmental Protection Agency
(EPA), the Centers for Disease Control and Prevention
(CDC), and the United States Department of Agriculture (USDA) all consider bed bugs a public health pest.
However, bed bugs are not known to transmit or spread
disease.
Bites on the skin are a poor indicator of a bed bug
infestation. Bed bug bites can look like bites from
other insects (e.g., mosquitoes, spiders), rashes (e.g.,
eczema, fungal infections), or even hives. Some people
do not react to bed bug bites at all. Bed bug bites can
be misidentied, which gives the bed bugs time to
spread to other areas of the house.
A more accurate way to identify a possible infestation of bed bugs is to look for physical signs of the
pest. For example, noting spots on bedding (about this
size: •) that are bed bug excrement is one of the earliest
and most accurate methods. The increase in bed bugs
in the United States may be due to more travel, lack of
knowledge about preventing infestations, increased
resistance of bed bugs to pesticides, and ineffective
pest control practices. Eradication measures for bed
bugs can be found at www.epa.gov/bedbugs/#identify.
Herpes Simplex Virus
HSV lesions have grouped vesicles that are surrounded
by an erythematous base, with discrete, well-demarcated areas that later crust. The condition is associated
with soreness and/or pain and may be preceded by
tingling. There is a predilection for lips and genitalia.
Recurrences in the same location are common and usually milder.
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Chapter 28 • Rashes and Skin Lesions
Herpes Zoster (Shingles)
Herpes zoster lesions present as clustered vesicles that
follow a dermatome. Lesions are surrounded by an erythematous base, with discrete, well-demarcated lesions
that later crust. Intense burning and pain often precede
the eruption. Herpes zoster along the ophthalmic
branch of the trigeminal nerve requires an immediate
ophthalmology visit as this can lead to zoster of the eye
and resultant blindness.
Varicella Zoster (Chickenpox)
Varicella lesions are discrete vesicles with a disseminated distribution; lesions develop in crops or in succession. Vesicles later crust, and occasionally secondary
impetigo develops. The illness is associated with
malaise and fever. This is a self-limiting condition.
Varicella zoster can later be reactivated as shingles in
patients over 50 or those who are immunosuppressed.
A shingles vaccination is recommended for all adults
60 years and older to reduce the risk of shingles.
Fungal Infections
Candidiasis
Candidiasis is a yeast that produces rashes at a variety
of sites; these rashes are called vulvovaginitis, thrush,
intertrigo (groin, axilla, gluteal), and diaper dermatitis.
The lesion is an erythematous maculopapular eruption
that is well demarcated, occasionally with satellite
lesions (pinpoint papules) at the periphery with
maceration in moist areas. It is associated with mild to
intense pruritus; the causative organism usually is
Candida albicans.
Tinea
Tinea is a fungal eruption that causes rashes at a
variety of sites: body (corporis), foot (pedis), beard
(barbae), groin (cruris), and scalp (capitis). Lesions
have erythematous scaling areas with a discrete border
and central clearing that is often associated with
pruritus or soreness. The causative organisms are
Trichophyton, Microsporum, and Epidermophyton.
Pityriasis (Tinea) Versicolor
Pityriasis versicolor is a yeast infection characterized by
a macular eruption of many colors, hypopigmentation to
hyperpigmentation, and ne scaling. Macules begin insidiously, may take weeks to months to fully develop,
and may coalesce. The condition is usually asymptomatic but occasionally pruritic. There is a predilection for
a sebaceous gland distribution (neck, trunk). The causative organism is Pityrosporum orbiculare (Malassezia
globosa). Repigmentation may take years or may never
occur. Recurrences are common.
Immunological and Inflammatory Eruptions
Eczema
Eczema is a chronic relapsing inammatory condition
that can take several forms (atopic, nummular, or dyshidrotic). Erythematous macules, papules, and vesicles
that occasionally weep and/or crust characterize eczema.
When severe, eczema may produce ssuring and bleeding. It is associated with mild to intense pruritus. In
dark-skinned people, scaling and dryness associated
with eczema give an “ashy” appearance to the skin.
Contact/Allergic Dermatitis
Contact dermatitis is an inammatory reaction to many
substances (e.g., poison ivy, nettles, rubber, nickel).
Papulovesicular or bullous eruptions surrounded by
erythema, with weeping of exudate (noncontagious)
are characteristic of the condition. It may be associated
with moderate to intense pruritus.
Psoriasis
Psoriasis is a chronic, relapsing autoimmune disorder
characterized by well-demarcated erythematous
plaques, patches, and papules, which typically present
with silvery scales. There is a predilection for the
elbows, knees, hands, nails (pitting), scalp, and gluteal
cleft. The condition may be pruritic or sore. The
lesions may demonstrate Auspitz sign: pinpoint bleeding when the surface is scraped.
Seborrheic Dermatitis
Seborrheic dermatitis is a chronic, relapsing disorder
characterized by erythematous scaling patches, which
are poorly demarcated and may be pruritic. There is a
predilection for the scalp, nasolabial folds, ears, face,
central chest, and genitals. The condition is aggravated
by cold weather, dry skin, and stress.
Allergic Reactions
Erythema Multiforme
Erythema multiforme is an immune complex disorder
involving the skin and occasionally the mucous membranes. Iris (target) lesions appear on the extremities
and desquamation often follows. Common causes include medications (especially sulfonamides, penicillins,
barbiturates, salicylates), histoplasmosis, Mycoplasma,
HSV, mononucleosis, hepatitis B, and malignancies.
Erythema multiforme minor is often self-limited. More
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