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B. Physical Examination. The morphology of the cutaneous eruption, distribution and esti-
mated percentage body surface involvement, presence of mucosal disease, and/or systemic
signs are important determinants of disease subtype and severity (2–4). EM minor manifests
as target or iris lesions that are symmetrically distributed and are found primarily on the
extremities (e.g., palms, soles) and sometimes on the face or trunk. The lesions develop over
10 days or more and resolve on their own, usually in 1–6 weeks. Recurrences are common
and may continue for years. EMM spans a wide range of presentations ranging from a severe
variant of EM minor to mild SJS. There is, however, more extensive mucosal involvement.
Lesions that are irregular or occur in large erythematous patches, blister, or bullae with
sloughing in large sheets are highly suggestive of SJS and the more severe TEN.
Systemic signs, such as a high fever, are seen primarily in SJS and/or TEN. In richly
pigmented skin, erythema may be underappreciated.
C. Testing. The diagnosis of EM and the closely related conditions discussed above are based
primarily on clinical findings. Nevertheless, histologic assessment (3) of lesional skin may
be of help, especially when the morphology of the cutaneous lesions are atypical and/or to
exclude other diagnoses. Other ancillary tests that may be helpful, especially if an underlying
infectious etiology is suspected, include a complete blood count, throat culture, antistrep-
tolysin-O titer, testing for infectious mononucleosis, HSV serology (immunoglobulin (Ig)
M and IgG), and a hepatitis screen. A chest radiograph may be obtained if Mycoplasma
pneumoniae, histoplasmosis, coccidiomycosis, or TB is suspected.
D. Genetics. There is no well-defined genetic basis to EM and its related group of dis-
eases. The exception is SJS/TEN secondary to carbamazepine and allopurinol in persons of
Chinese and South Asian origin, where specific HLA haplotypes (HLA-B*1502 and HLA-
B*5801, respectively) have been found to be of relevance (4, 7).
IV. DIAGNOSIS
A. Differential Diagnosis.
A fixed, discrete, annular, erythematous eruption, which lasts for
1–6 weeks from onset to healing and is self-limited, acute, or episodic, satisfies the clinical
criteria for EM minor. A systemic, erythematous eruption, with irregular and target lesions,
blisters, sloughing, and a systemically unwell patient, is much more indicative of SJS/TEN.
Other differential diagnoses to consider in the setting of EM and its related group of diseases
include autoimmune bullous disease, other drug eruptions (e.g., morbilliform drug erup-
tions), figurate erythema, connective tissue disease (e.g., lupus erythematosus), pityriasis
rosea, polymorphic light eruption, urticaria, urticarial vasculitis, and even viral exanthems.
Clinical features and histologic findings may be of help in excluding these conditions, as
may collegial help from a dermatologist in difficult cases.
B. Clinical Manifestations. Determining which subtype of EM is present helps dictate
treatment and anticipate prognosis. EM minor is a limited illness with little morbidity and
mortality, although recurrences are common. SJS/TEN are often life-threatening illnesses
with considerable morbidity and even mortality.
V. TREATMENT. The management of EM and related diseases lacks significant evidence-based
data and is based primarily on anecdotal evidence (3, 4). Identification of the underlying trig-
gering factor and prompt withdrawal or treatment is key to management of these patients. EM
minor does not always require therapeutic intervention, but supportive therapy is important,
including the use of antihistamines and topical corticosteroids to alleviate cutaneous symptoms
and local anesthetic/antiseptic mouthwash for oral mucosal involvement. In the setting of
HSV-associated EM minor, antiviral therapy (e.g., oral aciclovir) has been shown to be effec-
tive. In particular, long-term low-dose prophylactic antiviral therapy, such as oral aciclovir, in
the setting of recurrent EM minor, is efficacious. The principles of managing SJS and TEN
include prompt withdrawal of the implicated drug(s), as well as supportive care. Management
is best undertaken in a hospital setting rather than in the community. Other ancillary measures
include use of systemic antibiotics, corticosteroids, and/or other immune modulating drugs.
Where there is extensive cutaneous and/or mucosal ulceration, patients are best managed in
an intensive care/burns unit, ideally by a multidisciplinary medical team. The management of
EMM is determined by the severity, being similar to EM minor or SJS.
298
REFERENCES
1. Auquier-Dunant A, Mockenhaupt M, Nalda L, et al. Correlations between clinical patterns and causes
of erythema multiforme majus, Stevens-Johnson syndrome, and toxic epidermal necrolysis: results of
an international prospective study. Arch Dermatol 2002;138:1019–1024.
2. Lamoreux MR, Sternbach MR, Hsu WT. Erythema multiforme. Am Fam Physician 2006;74(11):
1883–1888.
3. Al-Johani KA, Fedele S, Porter SR. Erythema multiforme and related disorders. Oral Surg Oral Med
Oral Pathol Oral Radiol Endod 2007;103(5):642–654.
4. Mockenhaupt M. The current understanding of Stevens-Johnson syndrome and toxic epidermal
necrolysis. Expert Rev Clin Immunol 2011;7(6):803–813; quiz 14–15.
5. Ono F, Sharma B, Smith C, et al. CD34+ cells in the peripheral blood transport herpes simplex
virus DNA fragments to the skin of patients with erythema multiforme (HAEM). J Invest Dermatol
2005;124(6):1215–1224.
6. Kokuba H, Aurelian L, Burnett J. Herpes simplex virus associated erythema multiforme (HAEM) is
mechanistically distinct from drug-induced erythema multiforme: interferonis expressed in HAEM
lesions and tumor necrosis factor in drug-induced erythema multiforme lesions. J Invest Dermatol
1999;113(5):808–815.
7. Roujeau, J.-C. (2013). Drug eruptions and ethnicity. In O. Dadzie, A. Petit, & A. Alexis, Ethnic
Dermatology: Principles and Practice. Oxford: John Wiley & Sons.
13.3
I. BACKGROUND. Maculopapular rash is a term used to describe any skin rash that contains
both macules and papules. The affected skin appears red and has multiple confluent bumps.
II. PATHOPHYSIOLOGY
A. Etiology.
When a maculopapular rash is associated with fever, an infectious cause should
be suspected. If no fever is present, allergic reaction is usually the cause. Serious infec-
tions, such as meningococcemia, disseminated gonorrhea, and Rocky Mountain spotted
fever (RMSF), may present with an acute onset of fever and a maculopapular rash (1, 2).
Occasionally, anaphylaxis starts as maculopapular rash with palmar or pharyngeal itching
(3). Maculopapular rash is rarely a presenting sign of internal malignancy (1).
B. Epidemiology. Maculopapular rash is associated with many different diseases. The
prevalence, morbidity, and mortality in various ages, sexes, and race populations reflect the
underlying disease.
III. EVALUATION
A. History.
A detailed history of present illness should be obtained. The location that was first
affected, the course of spread, associated symptoms such as fever, itch, burn, or pain, and any
similar previous attacks are determined. If the patient had similar rash before, the previous
treatment and response to the treatment should be determined. A history of contact with
individuals affected by a similar rash should be considered. The history should also include
any chronic medical illnesses and treatments the patient is already using or has just started.
Treatments should include any prescribed medication, over-the-counter medicine, and
herbal preparations. A history of allergy to foods or drugs should be included. The social his-
tory is also important; this includes occupation, hobbies, smoking, drug abuse, new sexual
partners, and travel (1).
B. Physical Examination. A thorough physical examination should be performed. The
distribution of the rash should be noted when conducting the skin exam (1, 4). Viral
exanthems such as rubeola and rubella usually start centrally on face and trunk, then spread
Maculopapular Rash
Naama Salem Al Kaabi
299
centrifugally. The rash of meningococcemia tends to start peripherally. It usually begins
as a macule with central petechiae which then progress to a nodule followed by a wide-
spread rash. Lesions of gonorrhea start acrally on limbs and digits. If a maculopapular rash
manifests on the palms and soles, conditions such as syphilis, rocky mountain spotted fever
(RMSF), and disseminated gonorrhea should be considered (1–3).
1. Head, Eyes, Ears, Nose, and Throat Examination. Examination of the scalp to detect
ticks is important if RMSF is suspected. Swelling of mucous membranes may be indica-
tive of early anaphylaxis. Koplik’s spots of measles may appear on oral mucosa (3).
2. Lung Examination. Wheezing may be associated with anaphylaxis (1).
3. Genitourinary Examination. Primary syphilis presents with chancre on genitals. After
chancre heals, the palmar lesions of secondary syphilis appears (1, 4). Purulent discharge
or evidence of pelvic inflammation may indicate gonorrhea (3).
4. Extremities Examination. Joint swelling is often present in meningococcemia, gonococ-
cemia, and rheumatologic conditions (3).
5. Neurologic Examination. Signs of meningitis may indicate meningococcemia or
RMSF (3).
C. Testing. The complete blood count (CBC) is valuable. An elevated white blood cell
count with a left shift may indicate a bacterial infection; lymphocytosis may indicate a viral
infection; eosinophil counts are sometimes increased with allergic reactions; and rarely,
myelogenous leukemias can present with rash and abnormalities on CBC. Other testing
should be performed on the basis of the most likely causes of the rash. Consider the rapid
plasma reagin test and testing for gonococcemia in sexually active patients. Consider a smear
and culture of any pustules, especially if meningococcemia or gonococcemia is suspected.
Cerebrospinal fluid examination is useful if meningococcemia is suspected; it is usually
negative in RMSF. Consider an erythrocyte sedimentation rate in the presence of joint
involvement.
D. Genetics. Maculopapular rash is mostly caused by infectious or allergic causes; therefore,
genetic factors are not likely to play a strong role in this condition.
IV. DIAGNOSIS
A. Differential Diagnosis.
Maculopapular eruptions are seen in infections including viral,
bacterial, spirochetes, and rickettsial infections. They are also seen in immune-mediated
syndromes and rheumatologic diseases.
1. Viral Exanthems. Viral infections that usually present with maculopapular rash include
rubeola (measles), rubella (German measles), Fifth disease, and roseola (5). Rubeola starts
with cough, conjunctivitis, and coryza, with a maculopapular rash appearing around the
fourth day of fever. Rash starts on the hairline and then it spreads downward, sparing
the palms and soles. It lasts 4–6 days before it fades, leaving yellow-tan pigmentation
and some desquamation. Koplik’s spots are often seen on the oral mucosa, particularly
during the prodrome (1, 5). Rubella is similar to measles but is less severe, lasts for shorter
period of time, and is associated with prominent occipital adenopathy. Severe birth
defect can result from rubella infection of pregnant women (1, 3). Roseola is caused
by human herpes virus 6, starting with a febrile prodrome of 3–4 days. Within 2 days
of defervescence, the rash starts. It is a diffuse rash that spares the face and hands and
resolves spontaneously (5).
2. Allergic Eruptions. They usually appear as dull rash that contains vesicles or bullae. It is
intensely pruritic and tends to appear on hands, arms, knees, and genitals symmetrically.
It starts within 1 week of starting the offending medication and resolves gradually after
stopping it (1, 4).
.
3. Bacterial Infection. Meningococcal and gonococcal bacteremia should be suspected in
acutely ill patients presenting with fever, tachycardia, tachypnea, hypotension, leukocy-
tosis, and meningeal signs (2). Secondary syphilis presents with a diffuse rash or localized
rash mainly on head, neck, palms, and soles. It is often preceded by a chancre, and it
usually takes 2–10 weeks after appearance of the chancre for the rash to appear (3, 4).
Lesions appear as brown-red or pink macules and papules. Scaly papules, pustules, and
300
acneiform lesions can also be found. Fever, lymphadenopathy, and splenomegaly may
accompany the eruption. Secondary syphilis may have recurrent symptomatic attacks
interspersed by symptom-free periods (1, 4).
4. Rocky Mountain Spotted Fever. It is caused by Rickettsia rickettsii. It has an abrupt
onset with fever, headache, myalgia, bradycardia, and leukopenia. The rash usually starts
at the fourth day of illness as pinkish-red maculopapules on the wrists and ankles. It
spreads toward the trunk and progresses to petechiae. Late on the disease, palms and
soles become involved (1–3).
5. Kawasaki’s Disease. A disease of unknown cause, occurring almost exclusively among
young children. It is characterized by high-grade fever, lasting 5 days or longer, conjunc-
tivitis, lymphadenopathy, and desquamation of the hands. Strawberry tongue is a com-
mon finding. Skin findings include a maculopapular to scarlatiniform rash with mucous
membrane involvement (1, 3).
REFERENCES
1. James W, Berger T, Elston D. Andrews’ diseases of the skin: clinical dermatology, 10th ed. Canada:
Saunders Elsevier, 2006.
2. Richard P, Natasha S, Dermatologic emergencies. Am Fam Physician 2010;82(7):773–780.
3. Ali A. Specialty board review: dermatology, a pictorial review, 2nd ed. New York, NY: McGraw Hill,
2010.
4. Bolognia J, Jorizzo J, Rapini R. Dermatology, 2nd ed. Philadelphia, PA: Mosby Elsevier, 2008: vol 1.
5. Wolff K, Lowella A, Katz SI, et al. Fitzpatrick’s dermatology in general medicine, 7th ed. New York, NY:
McGraw Hill, 2008: vol 2.
13.4
I. BACKGROUND. Disorders of pigmentation present as skin that is darker or lighter than nor-
mal. The major determinant of skin color is the activity of the melanocytes, i.e., the quantity
and quality of melanin production. These disorders can be localized or generalized. Disorders of
hyperpigmentation include melasma, freckles, lentigines, ashy dermatosis, café au lait macules,
pityriasis versicolor, phytophotodermatitis, acanthosis nigricans, drug eruptions, and postin-
flammatory hyperpigmentation. Disorders of hypopigmentation include vitiligo, pityriasis alba,
pityriasis versicolor, ash leaf macules, halo nevus, idiopathic guttate hypomelanosis, postinflam-
matory hypopigmentation, and hypomelanosis from physical agents.
II. PATHOPHYSIOLOGY
A. Etiology.
With some pigmentary disorders, the cause may be readily identified as heredi-
tary, sun induced, due to a medication, infectious, or inflammatory. In some cases, the cause
is less clear.
B. Epidemiology. The prevalence of these conditions varies widely with the specific disease.
However, these disorders affect all races, ages, and both genders.
III. EVALUATION
A. History.
The first step in the diagnosis of these disorders is to classify the problem as one of
hyperpigmentation or hypopigmentation (1). Table 13.4.1 contains historic data, including
onset, exacerbating and relieving factors, as well as associated symptoms.
B. Physical Examination
1. Disorders of Hyperpigmentation. Melasma is a common, acquired disorder, charac-
terized by symmetric, hyperpigmented patches with an irregular outline that occur most
commonly on the face. Exacerbating factors include pregnancy, oral contraceptives,
Pigmentation Disorders
Fatima Al Faresi
301
TABLE 13.4.1 Factors Used to Differentiate Between Hyperpigmentation
and Hypopigmentation
Onset
Exacerbating
factors
Relieving
factors
Associated
symptoms
Hyperpigmented disorders
Café au lait spots Birth or early
childhood
None Regress over
time
None
Melasma Onset of liver
dysfunction,
pregnancy,
phenytoin
use, oral
contraceptive
use
Worsening
liver disease
or ongoing
exposure
May improve
with removal
of offending
agents, but
rarely disap-
pears entirely
Usually none
Acanthosis
nigricans Increased weight,
insulin use
Weight gain
or the use
of insulin,
nicotinic
acid, gluco-
corticoids, or
estrogens
Improves with
weight loss
and removal
of offending
agents
Diabetes-related
symptoms
Halo nevus Severe sun expo-
sure in a youth,
especially in
Turner’s syn-
drome
Ongoing sun
exposure
Tends to disap-
pear with time
Usually none
Solar lentigines Older age with
earlier age sun
exposure
Ongoing sun
exposure
None Usually none
Pityriasis versicolor Exposure to
humidity and
heat
Ongoing
exposure to
humidity and
heat
Lower humidity,
treatment
Occasionally
mild pruritus
Drug-induced
hyperpigmentation
Drug exposure,
especially to
minocycline or
zidovudine
Reexposure
to causative
agent
Occasionally
fades with
removal of
offending
agents.
Minocycline-
induced
changes
are often
permanent
Usually none
Fixed-drug eruption Drug exposure,
(phenolphtha-
lein, salicylates,
tetracyclines,
and sulfon-
amides)
Reexposure
to causative
agent
May fade with
removal of
offending
agents, but
often remains
Sometimes
painful
(Continued)
302
and sun exposure. Freckles are small, red or light brown macules that are promoted
by sun exposure. They are most commonly found on the face, arms, and back. They
occur as an autosomal dominant trait and are most often found in individuals with
fair complexions. Lentigines are similar to freckles; however, these are persistent in the
absence of sun exposure (2). Café au lait spots are uniformly pale-brown macules that
vary in size from 0.5 to 20 cm and can be found on any cutaneous surface. Five or more
spots greater than 5 mm in diameter in prepubertal person or 15 mm in a postpubertal
person suggest the diagnosis of neurofibromatosis. Acanthosis nigricans, though not
primarily a disorder of pigmentation, appears as grayish brown velvety plaques in a
symmetric pattern in the axillae, neck, and folds of the breast and groin. It may be a
cutaneous marker of insulin resistance, malignancy, or obesity. Pityriasis versicolor is a
common fungal infection of the skin. Lesions begin as multiple small, circular macules
of various colors (white, pink, or brown) that enlarge radially located on the upper
TABLE 13.4.1 Factors Used to Differentiate Between Hyperpigmentation
and Hypopigmentation
Onset
Exacerbating
factors
Relieving
factors
Associated
symptoms
Phytophotodermatitis Exposure to
topical agents
containing
furocoumarins
(oil of berga-
mot, psoralens,
limes)
Ongoing expo-
sure to topi-
cal agents
containing
furocouma-
rins (oil of
bergamot,
psoralens,
limes)
Topical or oral
steroids,
antihistamines
Sometimes
painful
Inflammation With inflammation Ongoing
inflammation
Relief of
inflammation
Pain from
inflammation
Pityriasis alba Young children
(especially those
with eczema)
Drying agents,
sunlight
May fade with
moisturizers,
tends to
disappear at
puberty
Occasionally
itchy or
burning
Ash leaf macule Childhood None None If underlying
tuberous
sclerosis:
mental
retardation,
seizures, and
adenoma
sebaceum
Vitiligo 10–30 y of age Stress, illness,
personal
crises, skin
trauma
Progressive
illness
Guttate
hypomelanosis
Middle age and
older
None
( idiopathic
lesions)
None ( idiopathic
lesions)
None
(Continued)
303
back, shoulders, upper arms, neck, and chest. Drug-induced hyperpigmentation occurs
with minocycline, bleomycin, amiodarone, clofazamine, 5-fluorouracil, cyclophospha-
mide, hydroxyurea, and others. Phytophotodermatitis initially resembles sunburn, sub-
sequently becoming hyperpigmented. Postinflammatory hyperpigmentation represents
an acquired and localized increase in melanin following cutaneous inflammation or
injury.
2. Hypopigmented Disorders. Vitiligo is an acquired loss of pigmentation characterized
histologically by the absence of epidermal melanocytes. There is a fairly symmetric
pattern of white macules with well-defined borders affecting any part of the skin.
Over time, the macules often coalesce into larger depigmented areas. Vitiligo often
occurs at sites of trauma (Koebner phenomenon), such as around the elbows and
in sunburned skin. Pityriasis alba presents as nonspecific erythema and gradually
becomes scaly and hypopigmented. The face, neck, and arms are the most common
sites. Ash leaf macules are hypopigmented macules (oval, ash leaf shaped, or stippled)
that are concentrated on the arms, legs, and trunk and are associated with tuberous
sclerosis. A halo nevus is an area of depigmentation surrounding a typical pigmented
nevus. Guttate hypomelanosis is seen as small, 2–5 mm porcelain-white macules
with sharply demarcated borders. They are located on the exposed areas of hands,
forearms, and lower legs of middle-aged and older people. Various types of physical
injuries induce cutaneous hypomelanosis or amelanosis, including thermal burns,
freezing, UV radiation, lasers, ionizing radiation, and physical trauma from surgical
procedures.
C. Testing
1. Obtaining skin scrapings from pityriasis versicolor may reveal the characteristic “spaghetti
and meatball” appearance of Malassezia furfur on a KOH prep. Wood’s light often
reveals pale yellow fluorescence.
2. Neurologic examination should be considered in individuals with café au lait or ash leaf
macules.
3. A complete physical examination and evaluations should be considered for patients with
acanthosis nigricans to assess for the presence of a systemic process, such as diabetes or a
malignancy.
4. Examination of vitiligo with Wood’s light in a dark room accentuates the hypopigmented
areas. Vitiligo can be associated with other autoimmune disorders, such as thyroid
dysfunction (e.g., Graves’ disease, Hashimoto’s thyroiditis). Others include insulin-
dependent diabetes, pernicious anemia, Addison’s disease, and alopecia areata.
D. Genetics. Examples of the many known genetic defects causing hypomelanosis include
oculocutaneous albinism, piebaldism, Waardenburg syndrome, hypomelanosis of Ito, and
tuberous sclerosis. Some defects resulting in hypermelanosis include neurofibromatosis,
incontinentia pigmenti, LEOPARD syndrome, and Peutz-Jeghers syndrome.
IV. DIAGNOSIS
A. Differential Diagnosis.
Patients with pigmentary disorders are initially best classified
into disorders of excessive pigmentation or hypopigmentation. The history is useful in
eliciting inciting factors, especially drug- or inflammation-induced changes. Characteristic
appearances of the lesions further define the disorder. Biopsy of lesions is generally not
necessary, although selected lesions may require further testing to clarify the condition or a
suspected underlying disorder.
B. Clinical Manifestations. These vary according to the disorder.
REFERENCES
1. Hori Y, Takayama O. Circumscribed dermal melanoses. Classification and histologic features.
Dermatol Clin 1988;6:315.
2. Plensdorf S, Martinez J. Common pigmentation disorders. Am Fam Physician 2009;79(2):109–116.
304
13.5
I. BACKGROUND
Pruritus or itch is a sensation that provokes the desire to scratch. Pruritus is transmitted through
slow-conducting unmyelinated C-polymodal and possibly type A delta nociceptive neurons with
free nerve endings located near the dermoepidermal junction or in the epidermis (1).
II. PATHOPHYSIOLOGY
A. Etiology.
Many skin diseases present with localized or generalized pruritus. These include
contact dermatitis, dermatitis herpetiformis, atopic dermatitis, pediculosis, bullous pemphigoid,
mycosis fungoides, and psoriasis. In addition to primary dermatologic conditions, many systemic
disorders, such as renal failure, hepatitis, and hypothyroidism, can cause pruritus (Table 13.5.1).
B. Epidemiology. Systemic causes of pruritus are more common among older individuals,
particularly those with other comorbidities. Otherwise, the prevalence of the particular
dermatologic condition will vary by age group and setting.
III. EVALUATION
A. History.
A thorough history and physical examination will usually distinguish between
presentations associated with dermatologic or systemic disease and will further direct the
Pruritus
Nawar Al Falasi
TABLE 13.5.1 Causes of Pruritis
Examples
Skin diseases (4) Contact dermatitis, dermatitis herpitiformis, eczema, bullous
pemphigoid, mycosis fungoides, psoriasis, urticaria, pruitic
urticarial papules and plaques of pregnancy (PUPPP), xerosis,
dermatophyte infections
Endocrine disorders Carcinoid syndrome, diabetes mellitus (DM), thyroid disease,
parathyroid diseases(4)
Infectious diseases Hepatitis, HIV, pediculosis, scabies
Renal diseases Chronic renal failure, hemodialysis
Hematologic diseases Iron deficiency, polycythemia rubra vera (5), hypereosinophilic
syndrome, essential thrombocythemia, myelodysplastic
syndrome(6)
Cholestatic pruritus (7) Primary biliary cirrhosis, primary sclerosing cholangitis, chronic
hepatitis C, choledocholithiasis, obstructive carcinoma of the
pancreas/biliary system, cholestasis of pregnancy
Malignancies Hodgkin disease, non-Hodgkin lymphoma, leukemias,
paraproteinemias and myeloma, Carcinoid syndrome, Sipple
syndrome (multiple endocrine neoplasia), solid tumors,
including GI malignancies, CNS tumors, and lung cancer
Drugs Chlorpropamide, tolbutamide, phenothiazines, erythromycin,
anabolic steroids, oral contraceptives
Psychiatric diseases Anxiety, depression, delusion of parasitosis
CNS, central nervous system; GI, gastrointestinal; HIV, human immunodeficiency virus.
305
physical examination and indicate the need for laboratory evaluation. A history of an insidi-
ous onset of generalized pruritus is more consistent with a systemic disorder. A detailed drug
history will help to exclude medication-induced pruritus. A history of alcohol abuse may
indicate chronic liver disease. A review of potential emotional stresses and the mental health
history may suggest a psychiatric cause (1, 2).
B. Physical Examination. Physical examination assists in differentiating between systemic
causes of pruritus and that of primary dermatologic conditions. In the case of systemic
disease, patients may have normal-appearing skin or secondary lesions, such as excoriations,
lichenification, prurigo nodules, or signs of a secondary bacterial infection (2, 3). Jaundice,
thyromegaly, or a plethoric appearance may indicate a particular systemic condition.
Alternatively, characteristic skin lesions in a particular distribution may be pathognomonic
for a specific dermatologic condition.
C. Testing. In a suspected primary dermatologic cause of pruritus, investigations and skin
biopsy may be required to make a specific diagnosis (4).
In suspected dermatophyte infections, skin scrapings or hair samples often reveal the
presence of hyphae or spores on potassium hydroxide (KOH) testing with microscopic
examination.
In cases of systemic causes of pruritus, investigations appropriate to the condition are
indicated. Examples include the following:
1. Liver function tests in cholestatic pruritus.
2. Renal function tests in chronic renal failure.
3. Thyroid function tests in thyroid disease.
4. Iron studies in iron deficiency anemia.
5. Blood morphology in iron deficiency anemia, polycythemia vera, and paraneoplastic
pruritus (4, 5).
6. Viral load, serologic testing, and CD4 count in suspected human immunodeficiency
virus infection.
D. Genetics. Certain conditions that cause pruritus, such as atopic dermatitis, may be heredi-
tary, and a positive family history is often present.
IV. DIAGNOSIS
A. Differential Diagnosis.
It is important to differentiate whether the cause of pruritus
is primary or systemic in nature. Further evaluation proceeds from this point. In primary
dermatologic conditions, characteristic primary skin lesions or a characteristic distribution
of lesions is often present.
The differential diagnosis of pruritus is extremely broad (Table 13.5.1). Common
dermatologic causes of pruritus in the primary care setting include xerosis, or excessive
dryness of the skin, eczematous or contact dermatitis, psoriasis and urticaria, as well as
dermatophyte infections. Xerosis tends to present in older patients, during the winter, in
areas of low ambient humidity and with frequent bathing. Eczematous dermatitis tends
to occur on the flexural surfaces of the arms and legs and the volar surfaces of the wrists
and neck, particularly in children. Among young infants, the cheeks or forehead and the
lateral surfaces of the extremities are often involved. Psoriasis is often associated with a
characteristic scaly rash, and urticaria is characterized by the presence of erythematous
wheals and plaques. Dermatophyte infections typically present with characteristic skin
lesions or reveal the causative agent on skin scrapings. A careful, stepwise approach to the
patient with pruritus will reward the primary care clinician and patient with an accurate
diagnosis in almost all cases.
REFERENCES
1. Bernhard JD. Endocrine and metabolic itches. In: Itch: mechanisms and management of pruritus.
New York, NY: McGraw Hill, 1994:251–260.
2. Krajnik M. Understanding pruritus in systemic disease. J Pain Symptom Manage 2001;21(2):151–168.
3. Yosipovitch G. Itch associated with skin disease: advances in pathophysiology and emerging therapies.
Am J Clin Dermatol 2003;4(9):617–622. Ann Dermatol 2011;23(1):1–11.
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13.6
I. BACKGROUND. Fever with an accompanying rash represents diagnostic challenge for even the
most experienced clinician because this combination of signs may represent either a trivial or a
life-threatening illness.
II. PATHOPHYSIOLOGY. A useful way of approaching the differential diagnosis is to distinguish
among the various entities that cause fever and illness by the types of rash they commonly
cause. Although various febrile illnesses may present with more than one type of rash, this
grouping allows the clinician to look at fewer causes rather than the entire spectrum of possible
causes (1).
A. Petechial rashes are commonly associated with the following:
1. Treatable infections, including endocarditis, meningococcemia, gonococcemia, septice-
mia from any bacteria, Rickettsiosis (especially Rocky mountain spotted fever) (2).
2. Infectious causes not subject to acute treatment, including enterovirus, dengue fever,
hepatitis B virus, rubella, and Epstein-Barr virus.
3. Noninfectious causes including deep venous thrombosis, superficial thrombophlebitis,
relapsing polychondritis, and erythema nodosum.
B. Maculopapular rashes are commonly associated with the following:
1. Treatable infections, including typhoid, secondary syphilis, meningococcemia, gonococ-
cemia, Mycoplasma, and Lyme disease.
2. infectious causes not subject to acute treatment, including enterovirus, parvovirus B 19,
human herpes virus 6, rubeola, rubella, adenovirus, and primary human immunodefi-
ciency virus (HIV).
3. Noninfectious causes, including allergy, erythema multiforme, systemic lupus erythema-
tosus, dermatomyositis, serum sickness, and juvenile rheumatoid arthritis.
C. Vesiculobullous rashes are commonly associated with the following:
1. Treatable infections, including staphylococcal large vesicle impetigo and toxic shock
syndrome, gonococcemia, rickettsial pox, herpes zoster, herpes simplex virus, Vibrio
vulnificus sepsis, and folliculitis.
2. Infectious causes not subject to acute treatment, including enterovirus, parvovirus B 19,
and HIV (although none of these three commonly present in this manner).
3. Noninfectious causes including eczema vaccinatum, and erythema multiforme bullosum.
D. Diffuse erythematous rashes are commonly associated with the following:
1. Treatable infections, including streptococcal scarlet fever, toxic shock syndrome, ehrli-
chosis (3), and Kawasaki disease.
2. Infectious causes not subject to acute treatment, including enterovirus infections.
3. Noninfectious causes of erythema are only rarely associated with fever.
Rash Accompanied
byFever
Mohammad Balatay
4. Bellmann R, Feistritzer C, Zoller H, et al. Treatment of intractable pruritus in drug induced cholestasis
with albumin dialysis: a report of two cases. ASAIO J 2004;50(4):387–391.
5.
Yosipovitch G. Chronic pruritus: a paraneoplastic sign. Dermal Therapy 2010;23(6):590–596.
6. Bernhard JD. General principles, overview, and miscellaneous treatments of itching. In: Itch: mecha-
nisms and management of pruritus. New York, NY: McGraw Hill, 1994:367–381.
7. Tejesh P. Therapy of pruritus. Expert Opin Pharmacother 2010;11(10):1673–1682.
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