7 - ERYTHEMA AND URTICARIA Flashcards
Erythema multiforme minor is usually caused by
HSV infection
Erythema multiforme major is most often caused by
Mycoplasma infection
Recurrent self limited disease Sharply marginated, erythematous macules then evolve to papules Target lesions observed in palms and soles Koebner phenomenon
EM minor
Type of EM: Frequently accompanied by a febrile prodrome Lesions on extremities and face, may include trunk Mucous membrane disease prominent
EM major
Sharply marginated rapidly extending, tender, erythematous or violaceous, painful, elevated plaque, 2-10cm diameter Face, neck, upper trunk and extremities May burn but do not itch Fever
Sweet syndrome Acute febrile neutrophilic dermatosis
Majority of cases of Sweet syndrome follow this infection
URTI
Pregnancy associated Sweet syndrome usually presents in what trimester
1st or 2nd
Treatment for Sweet syndrome
Self limited Oral prednisone 1mg/kg/day
Begins as an inflammatory pustule with a surrounding halo that enlarges and begins to ulcerate Lower extremities and trunk
Pyoderma gangrenosum
Least aggressive form of pyoderma gangrenosum
Vegetative
Disease most often associated with pyoderma gangrenosum
IBD
Most common inherited auto inflammatory syndrome
Familial Mediterranean fever
Autosomal recessive Recurrent 12-72h of fever and monoarthritis and erysipela like erythema
Familial Mediterranean fever
Treatment for familial Mediterranean fever
Colchicine
Vascular reaction of the skin characterized by appearance of wheals surrounded by red halo or flare with severe itching Caused by localized edema
Urticaria
Acute and chronic urticaria timeline
Acute <6 weeks Chronic >6 weeks
Sharply localized edema or wheal with a surrounding erythematous flare after the skin has been stroked 2-5% of population
Dermatographism
Cholinergic urticaria is produced by the action of acetylcholine on what cell
Mast cell
Adrenergic urticaria is mediated by this hormone
Norepinephrine
Management of cholinergic and adrenergic urticaria
Adrenergic- propranolol Cholinergic- antihistamines
Angioedema in the absence of urticaria can be due to
Hereditary angioedema ACE inhibitor
intense flushing may be associated with
Rosacea
In patients with rosacea, exercise, ambient heat or cold, spicy foods, alcohol, and hot beverages are common triggers for flushing. Topical cinnamic aldehyde can induce flushing.
Drugs associated with flushing
niacin, hormonal agents, serotonin agonists, calcium channel blockers, cyclosporine, chemotherapeutic agents, antimicrobials (vancomycin, metronidazole, rifampin), disulfiram, bromocriptine, intravenous contrast material, vasodilators (nicotinic acid, nitroglycerine, sildenafil and related drugs), and glucocorticoids.
Define eryhthema
The term erythema means blanchable redness (hyperemia) of the skin.
Erythema Palmare
Erythema palmare, or persistent palmar erythema, is usually most marked on the hypothenar areas and is associated with an elevated level of circulating estrogen. Cirrhosis, hepatic metastases, and pregnancy are common causes. Hereditary palmar erythema (Lane disease) has been rarely reported.
Generalized Erythema
Generalized erythema may be caused by medications, bacterial toxins, or viral infection. It is often uneven in distribution, being most noticeable on the chest, proximal extremities, and face. In general, these reactions are self-limited and resolve when the offending medication is stopped or the associated infection is treated or resolves. Specific exanthems associated with bacterial or viral infections are discussed in Chapters 14 and 19.
Erythema Toxicum Neonatorum
Erythema toxicum neonatorum occurs in a quarter to under half of healthy full-term newborns, usually on the second or third day of life. Because it is so common, dermatologists are usually consulted only for the most florid or atypical cases. Characteristically, the broad erythematous flare is much more prominent than the small follicular papule or pustule it surrounds (Fig. 7.1). Lesions involve the face, trunk, and proximal extremities and appear rarely on the soles or palms. There may be confluent erythema on the face. Fever is absent, and the eruption generally disappears by the 10th day. Erythema toxicum must be distinguished from miliaria, bacterial folliculitis, neonatal herpes, and scabies. When the rash is atypical, smears of the pustules demonstrating eosinophils are adequate to confirm the diagnosis. Rarely, a biopsy is required and demonstrates folliculitis containing eosinophils and neutrophils.
In 1860 von Hebra first described erythema exudativum multiforme. The original disease described by von Hebra is now called erythema multiforme minor (minus) or herpes simplex–associated erythema multiforme. It is strongly associated with a preceding herpetic infection. When multiple mucous membranes are involved, the lesions are more intense, and fever or arthralgias accompany the eruption, erythema multiforme major (majus) is diagnosed. This is most often caused by Mycoplasma infection. In contrast, StevensJohnson syndrome (SJS) and toxic epidermal necrolysis (TEN) usually represent adverse reactions to medications (see Chapter 6). As treatment and prognosis are related in part to the inciting agent, it is useful to classify erythema multiforme (EM) as follows:
- Herpes simplex–associated EM (HAEM)
- Erythema multiforme major (most often caused by Mycoplasma; some suggest the term mycoplasma pneumonia-induced rash and mucositis)
- Chronic oral EM
- Contact dermatitis–induced EM (see Chapter 6)
- Radiation-induced EM (see Chapter 6)
- Idiopathic
Herpes simplex–associated EM (HAEM) (erythema multiforme minor)
HAEM (erythema multiforme minor) is a recurrent self-limited disease, usually of young adults, occurring seasonally in the spring and fall, with each episode lasting 1–4 weeks. The individual clinical lesions begin as sharply marginated, erythematous macules, which become raised, edematous papules over 24–48 hours. The lesions may reach several centimeters in diameter. Typically, a ring of erythema forms around the periphery, and centrally the lesions become flatter, more purpuric, and dusky.
Three zones of Erythema multiforme
Fig. 7.2 Erythema multiforme, target lesions.
This lesion is the classic “target” or “iris” lesion with three zones: central dusky purpura; an elevated, edematous, pale ring; and surrounding macular erythema (Figs. 7.2 and 7.3).
Fig. 7.3 Erythema multiforme involving dorsal hands and penis.
The central area may be bullous. Typical targets are best observed on the palms and soles. Lesions generally appear symmetrically and acrally, with initial involvement most frequently on the dorsal hands. The dorsal feet, extensor limbs, elbows, knees, palms, and soles typically become involved. In about 10% of patients, more widespread lesions occur on the trunk. The Koebner phenomenon or photoaccentuation may be observed.
Fig. 7.4 Mucosal lesions of erythema multiforme.
Mucosal involvement occurs in 25% of cases and is usually limited to the oral mucosa. Oral lesions may appear as indurated plaques, target lesions, or erosions (Fig. 7.4).
An atypical variant of HAEM has been described in women. It consists of outbreaks of unilateral or segmental papules and plaques that may be few in number or solitary. Lesions may be up to 20 cm in diameter. The plaques are erythematous and evolve to have a dusky center, which desquamates. Subcutaneous nodules resembling erythema nodosum may be simultaneously present. Histologic examination shows features of EM, and herpes simplex virus (HSV) DNA may be identified in the lesions by polymerase chain reaction (PCR). Acyclovir suppression prevents the lesions.
Erythema multiforme major is frequently accompanied by a febrile prodrome and sometimes arthralgias. It occurs in all ages, is centered on the extremities and face, but more often than EM minor may include truncal lesions, which are papular and erythematous to dusky in color. Mucous membrane disease is prominent and often severely involves the oral mucosa and lips with hemorrhagic sloughing; less commonly the genital and ocular mucosa may be involved as well (Fig. 7.5).
Fig. 7.5 Ocular erythema multiforme.
How is SJS distinguised from EM?
SJS is distinguished morphologically by the presence of purpura or bullae in macular lesions of the trunk (Fig. 7.6).
Fig. 7.6 Stevens-Johnson syndrome.
In children, polycyclic urticarial lesions often become dusky centrally and are frequently misdiagnosed as EM. This presentation of urticaria has been dubbed “urticaria multiforme.” It represents urticaria, and histologic changes of EM are never present.
