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ESSENTIALS OF DIAGNOSIS

ESSENTIALS OF DIAGNOSIS

Erythema multiforme

  • Herpes simplex is most common cause.

  • Cutaneous lesions are true three ring targets.

  • Presents on the extensor surfaces, palms, soles, or mucous membranes.

  • Disease remains localized.

Stevens-Johnson syndrome and toxic epidermal necrolysis

  • Stevens-Johnson syndrome: < 10% BSA detachment.

  • Stevens-Johnson syndrome/toxic epidermal necrolysis overlap: 10–30% BSA detachment.

  • Toxic epidermal necrolysis: > 30% BSA detachment.

  • Medications are most common cause.

  • Cutaneous lesions are targetoid but often not true three ring targets.

  • Favors the trunk.

  • Involves two or more mucous membranes.

  • May progress to significant BSA involvement and may be life-threatening.

GENERAL CONSIDERATIONS

Erythema multiforme is an acute inflammatory skin disease that was traditionally divided into minor and major types based on the clinical findings. Approximately 90% of cases of erythema multiforme minor follow outbreaks of herpes simplex and is preferably termed “herpes-associated erythema multiforme.” The term “erythema multiforme major” has largely been abandoned.

SJS is defined as atypical target lesions with less than 10% BSA detachment; TEN is defined as lesions with greater than 30% BSA detachment; and patients with SJS/TEN overlap have between 10% and 30% BSA detachment. The abbreviation SJS/TEN is often used to refer to these three variants of what is considered one syndrome. SJS/TEN is characterized by toxicity and involvement of two or more mucosal surfaces (often oral and conjunctival but can involve any mucosal surface, including respiratory epithelium). SJS/TEN is most often caused by oral or, less commonly, topical medications, especially sulfonamides, NSAIDs, allopurinol, and anticonvulsants. In certain races, polymorphisms of antigen-presenting major histocompatibility (MHC) loci increase the risk for the development of SJS/TEN. For example, screening for HLA-B*5801, which is associated with allopurinol-induced SJS/TEN, is recommended in Han Chinese, those of Thai descent, and Koreans with stage 3 or worse CKD before initiation of allopurinol (see Chapter 20). Mycoplasma pneumoniae may trigger a mucocutaneous reaction with skin and oral lesions closely resembling SJS in children/young adults, which tends not to progress to TEN-like disease and carries an overall good prognosis.

CLINICAL FINDINGS

A. Symptoms and Signs

A classic target lesion, as in herpes-associated erythema multiforme, consists of three concentric zones of color change, most often on acral surfaces (hands, feet, elbows, and knees) (Figure 6–34). SJS/TEN presents with raised purpuric target-like lesions, with only two zones of color change and a central blister, or nondescript reddish or purpuric macules favoring the trunk and proximal upper extremities (Figure 6–35) (eFigure 6–102). Pain on eating, swallowing, and urination can occur if relevant mucosae are involved (eFigure 6–103).

eFigure 6–102.

A: Erythema multiforme on the palm with target lesions that have a dusky red and white center. B: Erythema multiforme with target lesions on the palms secondary to an outbreak of oral herpes. C: Erythema multiforme with vesicles and blistering ...

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