Page 613 - Clinical Immunology_ Principles and Practice ( PDFDrive )

590 ParT fivE Allergic Diseases

reliable results can be obtained with a dermographometer applied urticaria presents some difficulty, as antihistamines are only of
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at 100 g/mm for 70 seconds. The reaction should be assessed limited value.
after 2–6 hours. DPU is difficult to treat because it responds
poorly to antihistamines. Solar Urticaria
Solar urticaria affects about 1% of all patients with urticaria
Vibratory Angioedema and has a slight female predominance. It can be associated with
Vibratory angioedema is rare. Familial cases have been described. erythropoietic porphyria. Wheals are caused by electromagnetic
Local swelling develops several minutes to 6 hours after using wavelengths ranging from 290 to 760 nm (ultraviolet B [UVB],
vibrating machinery, lawn mowing, applauding, and jogging, UVA, and visible spectrum). It develops within minutes or hours
for instance. Systemic symptoms may occur (headache, chest after sun exposure and fades within 24 hours. Lesions are usually
tightness, diffuse flare). Placing the elbow or hand on a laboratory confined to sun-exposed skin, although they can also develop
vortex for 5–15 minutes is a useful challenge test. Avoidance of under clothing. The severity of solar urticaria depends on the
the trigger is the only helpful treatment strategy. wavelength, intensity, and duration of irradiation. Short exposures
induce flare and pruritus, whereas longer exposures cause wheal-
Thermal or Ultraviolet-Induced Urticaria ing. In patients sensitive to the visible spectrum, reactions may
Cold Urticaria occur through window glass.
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Cold urticaria accounts for about 3% of physical urticarias. It Solar urticaria is diagnosed by phototesting. Patients are
occurs in both children and adults and is more common in cold advised to use creams with a high sun protection factor (SPF),
climates, in women, and in atopic patients. The majority of cases protective clothing, and protective window shields and to limit
are primary with no identifiable cause, but some cases are second- the time spent outdoors.
ary to internal disease. Clinical manifestations can be local or
generalized. Mucosal involvement may develop after drinking Other Patterns of Inducible Urticaria
cold beverages. Systemic symptoms may be respiratory (laryngeal Cholinergic Urticaria
angioedema, tongue or pharyngeal swelling, wheezing), vascular Cholinergic urticaria is the second most common physical
(hypotension, tachycardia), GI (hyperacidity, nausea, diarrhea), urticaria and occurs mainly in adolescents, young adults, and
or neurological (disorientation, headache). Cold-induced urticaria patients with atopy. Cholinergic urticaria usually follows a rise
can be evoked by low ambient temperature, contact with cold in core temperature resulting from physical exercise, fever, or
objects, food or beverages, or immersion in cold water. Wheals external passive heat (hot bath, shower, sauna) but may also be
develop during the cold exposure or, more commonly, on provoked by emotional stress and spicy food. The characteristic
rewarming. The severity of cold urticaria depends on the intensity lesions are highly pruritic pinpoint pale wheals of 1–3 mm
and duration of the cold stimulus. Cold urticaria is potentially surrounded by a red flare. The wheals may occur anywhere
life threatening, with a risk of anaphylaxis and death on exposure except the soles and palms. Lesions usually begin on the trunk
of large skin areas to cold, for example, jumping into cold water and the neck, extending outward to the face and limbs. As
and hypothermia in neurosurgical and cardiothoracic operations. lesions progress, confluent areas of whealing and redness may
Familial cold urticaria is caused by mutations in the cold-induced develop. Severely affected patients may develop angioedema and
autoinflammatory syndrome (NLRP-3) gene and is no longer even anaphylaxis. Most patients with mild disease do not seek
classified as an inducible urticaria. medical help. The rash is triggered by activation of cholinergic
In 1–5% of patients, cold urticaria is secondary to cryoproteins sympathetic innervation of sweat glands, but the mechanism of
(mainly cryoglobulins). These can be associated with infections activation remains unclear. Decreased blood protease inhibitor
(hepatitis C, infectious mononucleosis, syphilis, Mycoplasma levels have been reported, and this is the rationale for using
infection), autoimmune diseases, and lymphoreticular malignancy anabolic steroids to treat occasional severely affected individu-
(Waldenström macroglobulinemia, myeloma), but these are rare. als who are unresponsive to other measures. The prognosis is
Cold urticaria can precede these diseases by several years. Second- reasonably favorable, with spontaneous resolution within 8 years
ary cold urticaria can also be drug-related (penicillin, oral in most patients. However, 30% of patients are affected for over
contraceptives, ACEIs). 10 years.
The diagnosis of cold urticaria is confirmed by an ice cube Cholinergic urticaria can be confirmed by reproducing the
challenge or TempTest (Moxie, Berlin, Germany). Some atypical rash with exercise or passive heating in a hot bath at up to 42°C.
cold-induced urticarias have negative results in the ice cube test. Treatment is primarily with antihistamines, but beta-blockers,
The clinical workup in cold urticaria includes measurement danazol, ketotifen, and montelukast have also been used. The
of cryoproteins. Patients should be cautious about bathing or condition may be refractory for up to 24 hours, and this may
swimming in cold water and consuming cold food or drinks. enable patients to prevent attacks by taking daily exercise.
Antihistamine treatment is often helpful but does not prevent
anaphylaxis caused by swimming in cold water. In severe cold Aquagenic Urticaria
urticaria, tolerance induction may be attempted: this involves Aquagenic urticaria is very rare. It occurs in women more
depletion of mast-cell histamine by repeated cold exposure. often than in men and is triggered by water contact but not
after drinking water. Scattered small papular wheals, similar to
Heat Urticaria cholinergic urticaria but with a larger flare, appear within 10–20
Heat-induced urticaria is very rare. It is induced by local heating minutes of water contact and resolve in 30–60 minutes. Diagnosis
of the skin at 38–44°C. Challenge test is done by application of is made by using a challenge test in which a wet compress at
hot water in a tube or beaker at up to 44°C for 4–5 minutes body temperature is applied for up to 10 minutes on whichever
or TempTest (Moxie, Berlin, Germany). Symptoms develop part of the body is usually affected. Associations with HIV and
several minutes after exposure. Management of heat-induced hepatitis B infection have been described.