**9.3 Physical treatment modalities**

#### **9.3.1 Phototherapy and photochemotherapy**

Phototherapy has been used for psoriasis for more than 100 years. Ultraviolet (UV) is known to exert an immunosuppressive effect through an effect on local and circulating immune cells, particularly on dendritic cells. Narrow band UV B of 311 nm has been shown to be most effective. Photochemotherapy combines the use of UV, usually UV A, with the topical or systemic administration of a photosensitizing agent, most commonly a psoralen. In contrast to skin psoriasis, nail psoriasis barely responds. In a study with oral PUVA on 10 patients, the skin of the proximal nail fold improved, but pitting did not improve. Nail plate crumbling cleared in three out of 4 individuals whereas onycholysis and oil drops improved slightly by approximately 50% (Marx and Scher, 1980). In contrast, in a retrospective study on the effect of different systemic treatments, PUVA improved the NAPSI score after 12, 24 and 48 weeks by 21%, 51% and 69%, Re-PUVA (combination of a retinoid with PUVA) by 27%, 65%, and 85%, ReNUVB (retinoid plus narrow-band UV B) by 21%, 48% and 64%, respectively, whereas narrow-band UV B alone had no beneficial effect (Regana et al, 2011). Topical PUVA resulted in clearing of 2 subjects with pitting and 2 with onycholysis improved substantially (Handfield-Jones et al, 1987). Even these results are surprising as the nail is a very efficient UV shield (Stern et al, 2011).
