The appliance according to the invention for dermatological or cosmetic treatment of a patient comprises a base body (19 6c19 59), which has a radiation source (11 6c11 21 41 61) for emitting light in a wavelength range between 350 nm and 1000 nm. An intermediate piece (15 6c15, 6c22, 6c23, 6c25 25 35 45 55 550, 551 650) sitting on the base body (19 6c19 59) conveys the light from the radiation source (11 6c11 21 41 61) in the direction of a body region (214) of the patient to be treated. An attachment element (15 6c15, 6c22, 6c23, 6c25 25 35 45 55 550, 551 650) secured detachably on the light output end of the intermediate piece (15 6c15, 6c22, 6c23, 6c25 25 35 45 55 550, 551 650) is brought into direct contact with the body region (214) to be treated, in order thereby to introduce a dermatologically or cosmetically active substance (213), during irradiation with the emitted light, into the body region (214) to be treated. Alternatively, the attachment element (540) can also simply serve to adapt the radiation cross-section of the emitted light to the size and the irregularities of the body region to be treated.
