Annular Rashes

Annular rashes (from Latin “annulus” = ring; syn. circinate) are ring-shaped lesions, although their morphology can vary and may also present as irregular, oval, semiannular, target-like, polycyclic, serpiginous, or reticular lesions.

Differential Diagnosis

• Infectious
  –Dermatophytes: Microsporum, Trichophyton, Epidermophyton infections (tinea capitis, corporis, cruris, pedis)
  –Tinea versicolor: Superficial infection, caused by Malassezia furfur
  –Erythema migrans: Earliest sign in Lyme disease, at the site of the tick bite; typically 7–10 days after bite; initially an erythematous macule that expands to form a large, annular lesion (up to 70 cm, average 15 cm) if left untreated
  –Erythema marginatum: In about 10% of the patients with rheumatic fever and occasionally in juvenile rheumatoid arthritis; associated with active carditis
  –Pityriasis rosacea
  –Secondary syphilis
  –African trypanosomiasis: Circinate outline and normal central area
  –Larva migrans cutanata: Can present with a serpiginous rash
  –Lupus vulgaris (rare, chronic, progressive form of cutaneous tuberculosis)

• Numular eczema
• Pityriasis alba
• Seborrheic dermatitis

• Immune mediated
  –SLE
  –Urticaria
  –Erythema multiforme, minor and major (including Stevens-Johnson syndrome): Hypersensitivity syndrome to a variety of etiologies (mostly infectious in children, notably Mycoplasma, and sulfonamides) and presentations; the hallmark is the target lesion (also occasionally seen in erythema annulare centrifugum and Kawasaki disease)
  –Toxic epidermal necrolysis (Lyell disease)

• Granuloma annulare
• Sarcoidosis
• Drug eruptions
• Cutaneous T-cell lymphoma

Workup and Diagnosis

• History
  –Age, diet, drugs, fever, tick bites
  –History of maternal conditions (e.g., SLE)
  –Association with other signs/symptoms, such as malaise, headache, myalgia, lymphadenitis, pharyngitis, cranial nerve palsies, subcutaneous nodules, arthritis, chorea, genital chancres

• Physical exam
  –Pattern and distribution of the rash; duration, spread mode, crops formation, presence of pruritus, involvement of the mucosal surfaces
  –Visualization of the pale or barely perceptible vascular reactive lesions can be enhanced by gentle warming of the skin
  –Wood lamp examination identifies Microsporum spp in tinea capitis, but misses Trichophyton; also useful in tinea cruris and tinea versicolor

• Labs
  –CBC with differential, ESR/CRP
  –Serology for SLE, Lyme disease, syphilis
  –Skin scrapings, KOH preparations, fungal cultures
  –Skin biopsy is rarely needed
• ECG if carditis is suspected
  –Prolonged PR interval
  –Atrioventricular block

Treatment

• Some annular rashes may not require treatment, but the condition that it is associated with them usually does
• Avoidance of the triggering agent and treatment with antihistamines and corticosteroids (for recalcitrant cases) in urticaria
• Antifungals for dermatophyte infections (oral griseofulvin if hair and nails are involved, topical clotrimazole, miconazole, or haloprogin for the others)
• Topical steroids and wet dressings for eczema, antibiotics for secondary infection
• Antibiotics
  –Lyme disease (doxycycline or ampicillin)
  –Syphilis (penicillin G)
• Skin sunlight exposure until mild sunburn occurs hastens the disappearance of lesions in pityriasis rosea
• Intensive care unit admission and support for severe conditions such as Stevens-Johnson syndrome and toxic epidermal necrolysis

Book Source Details

• Book Title: In A Page: Pediatric Signs and Symptoms
• Author(s): Jonathan E. Teitelbaum, Kathleen O. Deantonis, Scott Kahan
• Year of Publication: 2007
• Copyright Details: In A Page: Pediatric Signs and Symptoms, Copyright © 2007 Lippincott Williams & Wilkins.

Other Book Chapters Related to Rash

Read excerpts from these other book chapters related to Rash:

Copyright Details: In A Page: Pediatric Signs and Symptoms, Copyright © 2008 Williams & Wilkins.

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• Back to symptom: Rash: Introduction (review 1085 causes)
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More About This Book: Title: In A Page: Pediatric Signs and Symptoms Authors: Jonathan E. Teitelbaum, Kathleen O. Deantonis, Scott Kahan Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 1-4051-0427-9