The invention relates to a laser treatment head (1) for guiding a laser beam (2) to a target area (3) within a body cavity (4), and a laser system for thermal treatment of mucosa tissue (13) within a target area (3) in a body cavity (4), comprising said treatment head (1). A laser output element (5) including its deflection means (7) is rotatable relative to a guide element (6) about a longitudinal axis (8). First and second thread means (12, 13) engage each other such, that upon rotational movement of the laser output element (5) relative to the guide element (9) the deflection means (7) perform a combined axial and rotational movement relative to the guide element (9). A control unit (22) and the laser treatment head (1) are configured such, that the target area (3) is irradiated by individual pulses (p) in a helical pattern of irradiation spots (24,24', 24", 24"') over at least a section of the circumference of the body cavity (4). The control unit (22) is further configure such, that respective reference locations (X) on the target area (3) are irradiated by an individual pulse number (N) of subsequent pulses (p), thereby heating the mucosa tissue (23) within the target area (3) to a predetermined temperature.
