What is the updated protocol for diagnosis and management of erythema annulare centrifugum (EAC)?

Diagnosis and Management of Erythema Annulare Centrifugum

Diagnostic Approach

Erythema annulare centrifugum (EAC) is diagnosed clinically by the presence of slowly migrating annular or configurate erythematous lesions, most commonly presenting as large (>1 cm), scaly, erythematous, indurated plaques on the lower extremities, particularly the thighs. 1

Clinical Recognition

• Look for slowly enlarging annular erythematous lesions with a characteristic trailing scale at the inner border 1, 2
• The lower extremities, especially the thighs, are the most frequently involved locations (though any body site can be affected) 1
• Lesions typically appear as erythematous and urticarial papules or annular plaques that enlarge centrifugally 3
• The eruption is often chronic and recurrent, with a mean disease duration of 2.8 years in documented cases 1

Confirmatory Testing

• Perform a skin biopsy to confirm the diagnosis and classify the histopathologic subtype 1
• Histopathology distinguishes between superficial type (78% of cases) showing superficial perivascular lymphocytic infiltrate with a "coat-sleeve" pattern, and deep type (22% of cases) showing deeper dermal infiltration 1, 3
• The biopsy may reveal non-specific pityriasiform dermatitis in some cases, requiring clinicopathologic correlation 4

Investigation for Underlying Causes

Systematically search for associated conditions, as 72% of EAC patients have identifiable underlying diseases. 1

• Screen for cutaneous fungal infections (present in 48% of cases), particularly tinea pedis - examine interdigital toe spaces carefully for fissuring, scaling, or maceration 1
• Obtain fungal cultures or KOH preparation if fungal infection is suspected 1
• Evaluate for internal malignancy (present in 13% of cases), especially in patients with constitutional symptoms like weight loss, recent fractures, or other red flags 1, 4
• Consider age-appropriate cancer screening, particularly for lymphoproliferative disorders and solid tumors including colorectal adenocarcinoma 4
• Review all medications - EAC can be drug-induced, with documented cases associated with etizolam and other medications 2
• Investigate for viral infections including influenza, cytomegalovirus, and Epstein-Barr virus, particularly in recurrent cases 3
• Screen for other systemic diseases (present in 21% of cases) including sarcoidosis, connective tissue diseases, and other inflammatory conditions 1, 5

Management Protocol

Treatment of Underlying Causes

The primary management strategy is identification and treatment of the underlying trigger, as EAC is considered a hypersensitivity reaction to various antigens. 4

• If fungal infection is identified, treat aggressively with appropriate antifungal therapy 1
• Discontinue any suspected causative medications immediately - lesions typically resolve shortly after drug withdrawal 2
• Consider patch testing if drug-induced EAC is suspected 2
• If malignancy is identified (PEACE - Paraneoplastic Erythema Annulare Centrifugum Eruption), treatment of the underlying cancer is the definitive therapy 4
• For sarcoidosis-associated EAC, systemic corticosteroid treatment for the granulomatous disease improves the cutaneous manifestations 5
• Treat viral infections when identified as triggers 3

Symptomatic Treatment

Recognize that symptomatic treatments (systemic or topical corticosteroids and oral antihistamines) do not affect the chronic and recurrent course of EAC and provide only temporary relief. 1

• Topical corticosteroids can be used for symptomatic relief but do not alter disease progression 1
• Oral antihistamines may provide temporary symptomatic benefit 1
• Combination therapy with clarithromycin and calcipotriol-betamethasone has shown temporary efficacy in some cases, particularly those associated with viral triggers 3
• Local treatment may help lesions regress after a variable period in recurrent cases 3

Setting Realistic Expectations

Counsel patients that EAC is typically a chronic and recurrent disease despite treatment, with lesions often persisting for years. 1

• The disease follows a chronic course with a mean duration of 2.8 years, though individual variation is significant 1
• In recurrent cases, lesions may appear as frequently as every 2 weeks and require ongoing local treatment 3
• Even with identification and treatment of underlying causes, complete resolution may not occur 1
• The condition can be quite stressful for patients and may lead to unnecessary over-treatment if not properly recognized 1

Critical Pitfalls to Avoid

• Do not dismiss EAC as purely idiopathic without thorough investigation for underlying causes - 72% of cases have identifiable associated conditions 1
• Do not rely solely on symptomatic treatment with corticosteroids and antihistamines - these do not alter the disease course and the underlying trigger must be addressed 1
• Do not overlook malignancy screening in appropriate patients - EAC can be a paraneoplastic phenomenon (PEACE) requiring urgent oncologic evaluation 4
• Do not forget to examine for tinea pedis - fungal infection is the most common associated condition (48% of cases) and is treatable 1
• Do not continue suspected causative medications - drug-induced EAC resolves with medication discontinuation 2