Erythema Annulare Centrifugum: A Rare Skin Manifestation of Hashimoto Thyroiditis

Diffusive mediator feedbacks control the health-to-disease transition of skin inflammation

The spatiotemporal dynamics of inflammation provide vital insights into the understanding of skin inflammation. Skin inflammation primarily depends on the regulatory feedback between pro- and anti-inflammatory mediators. Healthy skin exhibits fading erythema. In contrast, diseased skin exhibits expanding erythema with diverse patterns, which are clinically classified into five types: circular, annular, arcuate, gyrate, and polycyclic. Inflammatory diseases with expanding erythema are speculated to result from the overproduction of pro-inflammatory mediators. However, the mechanism by which feedback selectively drives the transition from a healthy fading erythema to each of the five types of diseased expanding erythema remains unclear. This study theoretically elucidates the imbalanced production between pro- and anti-inflammatory mediators and prospective treatment strategies for each expanding pattern. Our literature survey showed that eleven diseases exhibit some of the five expanding erythema, thereby suggesting a common spatiotemporal regulation underlying different patterns and diseases. Accordingly, a reaction-diffusion model incorporating mediator feedback reproduced the five observed types of diseased expanding and healthy fading patterns. Importantly, the fading pattern transitioned to the arcuate, gyrate, and polycyclic patterns when the productions of anti-inflammatory and pro-inflammatory mediators were lower and higher, respectively than in the healthy condition. Further depletion of anti-inflammatory mediators caused a circular pattern, whereas further overproduction of pro-inflammatory mediators caused an annular pattern. Mechanistically, the bistability due to stabilization of the diseased state exhibits circular and annular patterns, whereas the excitability exhibits the gyrate, polycyclic, arcuate, and fading patterns as the threshold of pro-inflammatory mediator concentration relative to the healthy state increases. These dynamic regulations of diffusive mediator feedback provide effective treatment strategies for mediator production wherein skins recover from each expanding pattern toward a fading pattern. Thus, these strategies can estimate disease severity and risk based on erythema patterns, paving the way for developing noninvasive and personalized treatments for inflammatory skin diseases.

Evaluation of Clinicopathological Features and Associated Conditions in Erythema Annulare Centrifugum: A Retrospective Observational Analysis of 63 Patients

INTRODUCTION

Erythema annulare centrifugum (EAC) is a rare reactive disease that typically presents as annular or polycyclic erythematous lesions. There are few studies about EAC in the literature; therefore, data on the pathogenesis of the disease are limited.

OBJECTIVES

We aimed to examine the demographic, clinical, pathological characteristics and associated conditions of the patients with EAC.

METHODS

We analyzed records of the patients with EAC who admitted to our clinic in the last four years retrospectively.

RESULTS

A total of 63 patients, 39 women and 24 men, were included in our study. The mean age of the patients was 47.8±11.2 years. The mean disease duration was 15.54±12 months. The trunk and thigh were the most commonly involved sites (49%, 33%). Associated conditions were identified in 52.3% of the patients. Infections (N = 16), malignancies (N = 6), rheumatic diseases (n=4) and drugs (n=4) were the most common precipitating factors respectively. The most common infections were superficial fungal infections and Helicobacter pylori infection. Histopathologically, 10 patients had deep type and 53 patients had superficial type EAC. We determined that the disease duration from the onset of the disease was longer (12.3 versus 16.2 months) and the number of attacks (1.2 versus 2.8 attacks) was higher in the superficial type when compared to the deep type (P = 0.042, P = 0.038).

CONCLUSIONS

In our study, infections, malignancies and rheumatic diseases were among the most common etiologic factors. We would also like to draw attention to Helicobacter pylori infection as a precipitating factor which may be a novel finding.

Dermatologic Manifestations of Endocrine Disorders

Endocrine disorders are known to involve all organ systems of the body, including the skin. The cutaneous manifestations of endocrine disorders can range from common findings such as acanthosis nigricans, pretibial myxedema, acne, hirsutism, hyper or hypopigmentation to rare cutaneous findings such as miliaria rubra, calciphylaxis, lentigines, and calcinosis cutis. These cutaneous symptoms can sometimes be the presenting symptoms or can even be pathognomonic of the underlying endocrine condition. In some cases, the cutaneous symptoms from an underlying endocrine abnormality may be the most prominent. These symptoms can significantly affect the quality of life of individuals. Often, individuals may seek health care from a dermatologist or primary care physician for isolated skin symptoms. Therefore, it is imperative for physicians to recognize the skin symptoms as the manifestation of the endocrine disorder for prompt diagnosis and treatment of the underlying endocrine disorder.