Obsessed with purity and pain, the boundaries of blame and innocence, Skin is a fascinating meditation on psoriasis, the long-lasting chronic skin condition. Sergio del Molino, a Spanish writer and journalist, slowly guides us into his world of intense physical discomfort (most treatments of psoriasis only deal with its symptoms, rather than healing its immunological causes), but combines this private hell with provocative reflections on fellow sufferers. It’s a surprise to learn that Stalin shared something with Cyndi Lauper, John Updike, Pablo Escobar and Vladimir Nabokov.

The result is by turns macabre and compelling, with Del Molino using his affliction to put himself in the shoes of his pantheon of heroes and villains, considering how close he is to living aesthetic perfection or moral perversity.

The book starts with the author talking to his son, whose death as an infant he recounted in The Violet Hours. Reading Roald Dahl, father and son disagree; the former firmly affirms ‘witches don’t exist’, while the latter demurs gently. Leaving the boy to sleep, Del Molino writes:

"In the hall, before I get to the living room, I start scratching myself. My arms, my back, my hair. There are times when my scalp itches as though I’ve got witches’ eczema… I leave the door ajar and not wide open, so that [my son] isn’t tempted to get up, come through the living room and discover that witches not only exist, they are us, the parents.

He comes back to this point repeatedly. Psoriasis is much more than a skin disease; the pain it causes can lead its sufferers to intense self-reflection and fear.

On the one hand, this can result in the ‘monster’, cruel and spiteful, casting its pain onto the world. This is Stalin in a paddling pool in Sochi, his skin finding moments of peace in the sun and water, while the dictator plots and advances industrial-scale murder across the Soviet Union. The Cheka death chambers were ‘designed expressly with the cement floors on a slight incline to allow the blood to flow away’, Del Molino notes coldly.

On the other hand, pain can lead to saintliness: the sufferer seeking solace in love or art. Here, the author speaks of Updike falling in love with a librarian on a visit to Anguilla. The older man imagines a love affair with the girl, keenly aware of its potential transgressions, while keeping his genuine romance alive.

Psoriasis in Updike’s case (as it does later in the case of Nabokov and his wife Vera) highlights the love:

"There were great tracts of the psoriasis tattooing his arms and legs… it knocked the stuffing out of him to be seen like this by the younger woman with her black skin, as she handed over a couple of spy novels.

Del Molino writes with a soft touch, and his political, literary and cultural world is richly resonant throughout. Also, the meditations on how physical suffering can affect public actions and moral natures are stimulating. Non-psoriasis sufferers are invited to question how they would act or feel in various situations.

Nonetheless, the book fails to account for the deeper nature of good and evil. In the same way that psoriasis affects the skin but is caused at a much deeper immunological level, Skin seeks to account for morality by investigating what can be seen and talked about, rather than more ambiguous, ultimately untraced motivations.

Yes, Stalin and Escobar had a skin disease, but they are also unique — murderous to an extent that can’t be explained satisfactorily. Del Molino doesn’t pose the question, and so we are left to wonder why millions of psoriasis sufferers live their lives without turning into arch criminals.

All that said, Skin is frequently deeply moving and stylistically well achieved.