Photosensitive Seborrhoeic Dermatitis

Photosensitive Seborrhoeic Dermatitis

This article relates to Girl in the Dark

In Girl in the Dark, we hear a lot about how Photosensitive Seborrhoeic Dermatitis has impacted Anna Lyndsey's life but not so much about the condition itself.

Basic Seborrhoeic Dermatitis is, according to the Mayo Clinic, a common skin condition. Similar to eczema, it is characterized by red, inflamed skin, usually on the scalp, face, chest and back. Unsightly scaly patches are not unusual, and persistent dandruff is also a problem. While these symptoms, which range from unpleasant to painful, mean that flare-ups can be difficult to cope with, the disorder itself is not usually debilitating. Seborrhoeic Dermatitis does not usually adversely affect a person's ability to lead a relatively normal, fulfilled life. Anna Lyndsey's experience, however, was far from usual. Her particular misfortune was to develop a rare, life-crippling form of the disorder, one that is characterized by extreme light sensitivity. Anna became allergic to all forms of light - from the weakest indoor light bulb, to the fluorescent glare from her computer screen, to the most disabling of all, sunlight. Curiously, this would happen often without any discernibly visible evidence that her body was excruciatingly aflame.

So rare is Photosensitive Seborrhoeic Dermatitis that there are few statistics available. There are no helpful diagnostic shortcuts, no guidance on possible prognoses. Anna discovered, over the course of years of investigation, only one other person living with the disease in the UK. This lack of any sense of solidarity with fellow sufferers, coupled with the seclusion necessitated by the condition, means that patients become akin to ghosts, shadows of their former selves, spectres who are excluded from participation in the world at large.

Photosensitive Seborrhoeic Dermatitis is just one of a number of skin diseases caused by exposure to light. In the medical profession, they are called photodermatoses, and fall into four distinct causation categories: genetic (caused by DNA abnormalities), metabolic (when chemical reactions in the body disrupt normal functioning), exogenous (caused by external factors, usually reactions to certain drugs), or idiopathic (apparently spontaneous allergic reactions which can be traced to no known cause). Examples of genetic photodermatoses include Bloom's Disease (predominantly affecting Ashkenazi Jews) and certain forms of Lupus. Exogenous photodermatoses often occur as reactions to antibiotics, non-steroidal anti-inflammatory drugs, fragrances, and topical creams. Polymorphic Light Eruption, which presents as an angry red rash, and is characterized by sensitivity to both UV and visible light, is the most common type of idiopathic reaction.

Anna Lyndsey's light sensitivity is also idiopathic and so extreme as to render her a very rare statistical anomaly. Medical research is a numbers game - research dollars go to apparently "worthier" diseases, afflicting greater proportions of the population. As long as this continues to be the case, those affected by the condition will continue to live a kind of half-life, condemned indefinitely to a suffocating, soul-destroying world of darkness.

Filed under Medicine, Science and Tech

This "beyond the book article" relates to Girl in the Dark. It originally ran in April 2015 and has been updated for the February 2016 paperback edition. Go to magazine.