The impact of psychosocial stress on healthy skin.

Dermatologists are only too aware of the significant role psychosocial stress plays in the exacerbation of skin disease; indeed, it is often the first precipitant patients mention when they attend outpatient clinics. Of late, research has focused on understanding the 'brain-skin' axis, a complex interplay between the nervous and immune systems and the skin. In particular, there is an evolving body of literature exploring the underlying pathophysiological mechanisms by which psychosocial stress influences skin homeostasis. This article provides a broad overview of the literature, emphasizing the importance of individual stress perception and summarizing the varied roles of the major cutaneous stress-response pathways. Both central [the hypothalamic-pituitary-adrenal (HPA) axis and the locus ceruleus-norepinephrine (LC-NE) sympathetic adrenomedullary system] and peripheral (the intracutaneous HPA axis and the release of mediators from peripheral sensory and autonomic nerves) pathways are discussed. Moreover, how activation of these pathways affects the skin's immune system, barrier function, wound healing and susceptibility to infection is reviewed. Although this field of research is rapidly expanding, several important questions remain unanswered, including: what is the precise role of mast cells in the cutaneous stress response?; what is the role of regulatory T-cells?; can therapeutic intervention be harnessed to prevent the stress-induced exacerbation of skin disease? It is anticipated that an improved understanding of the underlying mechanisms through which psychosocial stress affects the homeostasis of healthy skin will not only increase knowledge of the brain-skin axis but will also improve the holistic management of stress-responsive cutaneous disease.

Erythema elevatum diutinum: a review of presentation and treatment.

Erythema elevatum diutinum (EED) is a rare, chronic and treatable skin condition. It has many histological mimics and is often associated with a variety of underlying systemic diseases, when these are present the management and prognosis dictates the course of the EED. This review aims to highlight the differential diagnosis, clinical manifestations of EED and the possible underlying systemic disease. It is important for clinicians to be aware that EED may predate underlying conditions and the presence of lesions may indicate underlying disease activity. In some cases one may need 'search' for underlying disease. Treatment of these lesions is notoriously difficult. Dapsone is used as the mainstay of treatment, however other options exist. We have highlighted different treatment options and suggested a treatment algorithm. In some cases, treatment may need to be targeted at underlying disease.

Sarcoid and the nail: review of the literature.

Nail involvement in sarcoidosis is rare, but its presence is often associated with chronic systemic disease. We have reviewed all 33 reported cases of nail involvement with sarcoidosis, including our own case. Nail changes in sarcoidosis, while rare, can include dystrophy (n=10, 30%), onycholysis (n=7, 21%), subungual hyperkeratosis (n=7, 21%), nail hyperkeratosis (n=2, 6%) and longitudinal ridging (n=8, 24%). All reported cases of nail sarcoidosis occurred in the setting of systemic involvement. In almost half of the cases, bony cysts were noted on radiological examination. The presence of nail dystrophy in a patient with sarcoidosis should therefore prompt radiological examination and investigation for systemic involvement.