Polymorphic photodermatosis as a disease of failed apoptotic clearance in immune-mediated inflammation and the description of a clinical case

Polymorphic photodermatosis is the most common, acquired skin disease characterized by an abnormal, recurrent, and delayed response to sunlight.

In this article, modern views on the etiology of pathogenesis are described clinical picture, differential diagnosis, principles of treatment and prevention of polymorphic photodermatosis. The pathogenesis of this disease is a form of delayed-type hypersensitivity reaction to photoantigens. The abnormal immune response has been attributed to the immunosuppressive effects of sunlight due to a breakdown in allergen tolerance and a disruption in the mechanisms of apoptosis.

The main symptoms of the disease are erythema and highly itchy elements of skin lesions, which are very diverse, most often represented by macules, papules and vesicles, or vesiculo-bullous, urticarial, hemorrhagic rashes, hence the name of the disease polymorphic photodermatosis. Usually one morphology prevails in one patient. The article presents a clinical case and the results of their own observations.

Studies of the pathogenesis of polymorphic photodermatosis have confirmed the presence of an abnormal immune response. The exact mechanism of immunosuppression caused by ultraviolet radiation and the relative contribution of UV-B and UV-A in healthy people are still unclear, but the expression of TNF-alpha, IL-4 and IL-10 and the depletion of Langerhans cells appear to be key phenomena.

Diagnosis of the disease based on the clinical picture. The need for differential diagnosis of various forms of polymorphic photodermatosis is due to their clinical and sometimes histological similarity with other skin formations. For more accurate verification of the diagnosis, a biopsy of the examined skin area is possible, followed by histology. The histology of polymorphic photodermatosis is nonspecific, in accordance with the polymorphic clinical picture, as well as depending on the timing of the biopsy.

Further studies of the pathological mechanisms underlying polymorphic photodermatosis may allow us to develop a more targeted approach to conservative treatment and prevention.