Erythema annulare centrifugum (EAC) is a rare skin disease characterized by round red patches appearing on thighs and legs for no apparent reason. Erythema annulare centrifugum has a clinical symptom similar to tinea corporis infection (fungal infection) but it is very different in terms of therapy.
Erythema annulare centrifugum is usually asymptomatic (with no symptoms) or itching varies in length in the thighs and legs, more commonly experienced by women aged from 16 to 83 years but the average age is 49 years. Erythema annulare centrifugum showed patches with red round plaque lesions sometimes similar to hives and extends centrifugally (from the middle of the body towards the outside) and the middle of the plaque looks healed. In western countries, lesions usually start from spring to summer and last for 15 days to 5 months and then disappear on their own in the winter or fall.
There are two types of EAC, the surface and deep type. In the deep EAC, the inflammatory process involves the middle layer of skin, whereas on surface lesion it does not. However, both have a similar histological picture, an inflammatory cell around the blood vessel.
The most body parts affected by EAC are the upper body and legs, especially around the buttocks and pelvic area. The process of EAC is not known accurately, but it is suspected that there is a hypersensitivity reaction (excessive reaction) to the stimulus from inside and outside the body.
Erythema annulare centrifugum is often associated with several infectious diseases both due to bacteria, viruses, mycobacteria, and parasites; hormonal disorders such as menstrual cycles, hypothyroidism, some foods and drinks such as salicylates, antimalarial drugs, cimetidine, amitriptyline, atizolam, and gold sodium thiomalate; as well as some malignancies can cause EAC. Furthermore, environmental factors may be influential such as temperature, plant season, and fungus that cause EAC to appear in certain seasons. However, the majority of EACs are not found to have clear causative factors (idiopathic EAC).
EAC treatment focuses on the clinical symptoms that accompany it. Both surface EAC and the deep can be treated with both systemic and topical corticosteroids. In certain circumstances, for example, itching may require systemic antihistamines.
Erythema annulare centrifugum has symptoms that are almost similar to tinea corporis (fungal infection). Tinea corporis is a dermatophyte fungal infection that attacks hairless skin and causes red lesions due to inflammation shaped like round red spots with raised edges. However, EAC and tinea corporis require very different therapeutic strategies.
A 52-year-old woman who came to Dr. Soetomo complained of having red patches on her legs and abdomen for two weeks. Firstly, small patch like insect bite appeared in her abdomen but rapidly spread into her extremities especially at lower legs accompanied with itchy. She never complains about pain and burning sensation on her rash. The patient was given methylprednisone, mebhidrolin, and sodium fusidate, but the rash did not disappear. The patient also complained of toothache since three months ago.
Physical examination result showed there were red patches with varying sizes. Initially, they were in the form of small red spots that unite into a round patch with a central part that appears to be healing and spread to the area of the hands and feet, and the patient complains of itching in the rash. All laboratory results were within normal limits, and no fungal infection was found in microscopic examination.
The patient was treated with dexamethasone 1 mg 3 times a day and cetirizine 10 mg twice a day. One week later, the patient still complained of itching and rashes. However, when ketoconazole was given, the patient felt the itchiness and burning. Finally, dexamethasone was continued, and ketoconazole was stopped. Then a skin biopsy is performed, and the results of the histological examination showed epidermis with spongiosis, histiocyte infiltration in the dermis, inflammation cells and eosinophil infiltration around blood vessels.
Based on clinical and histopathological results and supported by the presence of recurrent lesions, this patient was diagnosed with EAC. After three months the rash healed naturally. Factors causing EAC in this patient was suspected from the dental infection. When the dental infection is treated, patients responded better to corticosteroid treatment.
The prognosis of EAC patients was quite good, but it worsens if EAC is associated with malignancy and other systemic diseases. Sometimes EAC appears before, at the same time, or after the appearance of malignancy. Therefore, a physical examination and a proper diagnosis are needed so the treatment can be effectively given. (*)
Author: dr.Rahmadewi,Sp.KK
Details of this research available at:
https://e-journal.unair.ac.id/BIKK/article/view/12392
Erythema Annulare Centrifugum Mimicking Tinea Corporis: A Case Report
Rahmadewi, Riyana Noor Oktaviyanti
Department of Dermatology and Venereology, Faculty of Medicine, Universitas Airlangga / Dr. Soetomo General Hospital, Surabaya, Indonesia
