Erythema annulare centrifugum
A thorough body examination failed to reveal any other rashes or lesions suggestive of a fungal infection. A blood count and urinalysis were within normal limits. She had no lymphadenopathy or hepatosplenomegaly. A potassium hydroxide analysis of skin scrapings was negative for fungal elements. Punch biopsy of the skin on the left arm revealed focal intermittent parakeratosis, mildly acanthotic and spongiotic epidermis, and a tight superficial perivascular chronic dermatitis consisting of lymphocytes and histiocytes (Figures). Given these findings, a diagnosis of erythema annulare centrifugum (EAC) was rendered.
Courtesy Dr. Stephen F. Kirschbaum
Courtesy Dr. Stephen F. Kirschbaum
EAC is a rare, reactive skin rash characterized by redness (erythema) and ring-shaped lesions (annulare) that slowly spread from the center (centrifugum). The lesions present with a characteristic trailing scale on the inner border of the erythematous ring. Lesions may be asymptomatic or mildly pruritic and commonly involve the trunk, buttocks, hips, and upper legs. It is important to note that its duration is highly variable, ranging from weeks to decades, with most cases persisting for 9 months. EAC typically affects young or middle-aged adults but can occur at any age.
Courtesy Dr. Catalina Matiz
Although the etiology of EAC is unknown, it is believed to be a hypersensitivity reaction to a foreign antigen. Cutaneous fungal infections are commonly reported as triggers as well as other viral infections, medications, malignancy, underlying systemic disease, and certain foods. Treatment depends on the underlying condition and removing the implicated agent. However, most cases of EAC are idiopathic and self-limiting. It is possible that our patient’s prior history of tinea capitis could have triggered the skin lesions suggestive of EAC, but interestingly, these lesions did not go away after the fungal infection was cleared and have continued to recur. For patients with refractory lesions or treatment of patients without an identifiable cause, the use of oral antimicrobials has been proposed. Medications such as azithromycin, erythromycin, fluconazole, and metronidazole have been reported to be helpful in some patients with refractory EAC. Our patient wanted to continue topical treatment with betamethasone as needed and may consider antimicrobial therapy if the lesions continue to recur.
Tinea corporis refers to a superficial fungal infection of the skin. It may present as one or more asymmetrical, annular, pruritic plaques with a raised scaly leading edge rather than the trailing scale seen with EAC. Diagnosis is made by KOH examination of skin scrapings. Common risk factors include close contact with an infected person or animal, warm, moist environments, sharing personal items, and prolonged use of systemic corticosteroids. Our patient’s KOH analysis of skin scrapings was negative for fungal elements.
Jennifer Laborada
Erythema marginatum is a rare skin rash commonly seen with acute rheumatic fever secondary to streptococcal infection. It presents as annular erythematous lesions on the trunk and proximal extremities that are exacerbated by heat. It is often associated with active carditis related to rheumatic fever. This self-limited rash usually resolves in 2-3 days. Our patient was asymptomatic without involvement of other organs.
Like EAC, granuloma annulare is a benign chronic skin condition that presents with ring-shaped lesions. Its etiology is unknown, and lesions may be asymptomatic or mildly pruritic. Localized granuloma annulare typically presents as reddish-brown papules or plaques on the fingers, hands, elbows, dorsal feet, or ankles. The distinguishing feature of granuloma annulare from other annular lesions is its absence of scale.
Dr. Catalina Matiz
Urticaria multiforme is an allergic hypersensitivity reaction commonly linked to viral infections, medications, and immunizations. Clinical features include blanchable annular/polycyclic lesions with a central purplish or dusky hue. Diagnostic pearls include the presence of pruritus, dermatographism, and individual lesions that resolve within 24 hours, all of which were not found in our patient’s case.
Ms. Laborada is a pediatric dermatology research associate in the division of pediatric and adolescent dermatology at the University of California, San Diego, and Rady Children’s Hospital. Dr. Matiz is a pediatric dermatologist at Southern California Permanente Medical Group, San Diego. Ms. Laborada and Dr. Matiz have no relevant financial disclosures.
References
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