**2. Short history**

Photodynamic therapy is dating from ancient time, the Indian civilizations reported from the first time the combined action of psoralens with sunlight to treat vitiligo [14].

Niels Fiensen used UV light to treat small pox, pustular infections eruptions, cutaneous tuberculosis, and for its results he obtained the Nobel Prize in Medicine in 1903. Similar results obtained Niels Raab in 1905, by using eosin as sensitizer and combining his results with Jesionek and J.Prime results for skin tumors and epilepsy generated by light induced dermatitis [17]. Meyer-Betz was the only experimentalist who tested this method on himself, by injecting haematoporphyrin, reporting the observed effects: oedema, erythema and light sensitivity [18]. Later, Campbell and Hill studied the PDT effects on microcirculation, reporting the thrombosis and vascular shutdown [19].

Lipson in 1966 went on to treat a patient with a large cancer of the breast following an injection of a derivative of haematoporphyrin (HpD). The modern era of photodynamic therapy was established by Dr. T.J.Dougherty, at the Division of Radiation Biology at Roswell Park Memorial Institute, Buffalo, USA, who reported that a systematically injected porphyrin on activation with red light caused complete eradication of transplanted experimental tumors [20].
