Aclient is undergoing photochemotherapy involving a combination of a photosensitizing chemical and ultraviolet light. what health problem does this client most likely have?

Psoriasis is a skin disease that manifests itself in symptoms of varying severity. It is a chronic disease that can not be cured but can be alleviated by many treatments (like chemotherapy).
Photochemotherapy: also called P-UVA. It consists of the combination of UVA (a type of UV light) radiation after the local or oral administration of a psoralen that acts as a sensitizing photo. It is used alternately in patients for whom UVB (another type of UV) has no effect, as P-UVA is more effective and longer-lasting, but is associated with basiloma (basal cell carcinoma) and melanoma.