Erythema gyratum repens-like psoriasis

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.

A case of tinea incognita and differential diagnosis of figurate erythema

A patient with tinea incognita is presented together with a review of the literature of figurate erythema. Figurate lesions are emblematic for dermatology and perhaps the most picturesque efflorescences. The differential diagnosis can be broad and sometimes challenging. Many clinical entities with resembling primary and secondary efflorescences have to be considered as differentials and can be due to anti-infectious, paraneoplastic, allergic, autoimmune or other immune reactions.

A diagnostic protocol designed for determining allergic causes in patients with blood eosinophilia

BACKGROUND

Blood eosinophilia is a common laboratory abnormality, and its characterization frequently represents a quandary for primary care physicians. Consequently, in France, specialists and particularly hematologists, often must investigate patients who present with blood eosinophilia that often, but not always, occurs because of allergic causes. Both the Departments of Hematology and Parasitology at Toulouse University Hospitals established a collaboration to rule out allergic causes of eosinophilia, particularly helminthiases, prior to initiating more sophisticated investigations.

METHODS

Since 2004, the authors employed the same protocol to investigate eosinophilic outpatients who attended the clinic of Parasitology at Toulouse University Hospitals, and they reported the performance of this diagnostic procedure that was designed to be rapid (no hospitalization required) and only moderately expensive.

RESULTS

A total of 406 patients who presented with blood eosinophilia greater than 0.5 (×109, giga cells per litter, G/L) had an allergic etiology in 350 (86.2%) cases. Among the remaining 56 subjects, 17 did not undergo a follow-up and 39 were referred to another specialized department, mostly Hematology. However, only 21 patients attended then were subsequently investigated. Non-allergic causes of eosinophilia, including 3 cases of the lymphoid variant of hypereosinophilic syndrome and 2 cases of myeloproliferative disorder, were identified in 14 patients, whereas 7 remained diagnosed as having idiopathic eosinophilia.

CONCLUSION

This study underlines the need to investigate patients presenting with even moderate blood eosinophilia. The work-up that was employed appears to be efficient and versatile and may be used by any medical specialist, such as in hematology, infectious disease, or internal medicine departments, who needs to investigate eosinophilic patients and should initially rule out any etiology of allergic eosinophilia.

Tinea imbricata or Tokelau

Tinea imbricata (TI) or Tokelau is a superficial mycosis caused by Trichophyton concentricum, an anthropophilic dermatophyte. It is endemic in some islands of the South Pacific (Polynesia), South-East Asia, Central and South America, and Mexico, and is most often seen in individuals living in primitive and isolated conditions. The skin lesions are characteristically concentric and lamellar (imbricata: in Latin, tiled) plaques of scale. Predisposing conditions include humidity, inheritance, and immunologic factors. The diagnosis is usually made on clinical grounds, supported by skin scrapings and culture. Tokelau is a chronic and highly relapsing disease and, although no first-line treatment exists, best results are obtained with oral griseofulvin and terbinafine and a topical combination of keratolytic ointments, such as Whitfield's. TI is a disease model that allows the correlation of a series of environmental, genetic, immunologic, and therapeutic conditions.