Apparatus formed of a laser lucent hollow, transparent needle (10) with an optical fiber (12) disposed within its interior. Means such as a spacer (14) can be used to retain the fiber in position within the needle. In a particular embodiment, the end of the needle adjacent to the energy transmitting end of the fiber is closed, and energy scatterers or diffusers (18) may be provided to alter the characteristics of the transmitted energy. In further embodiments, scattering or diffusing materials (32) are disposed within the walls and the closed end (16) of the needle to form a laser lucent apparatus customized to specific hyperthermia requirements. In other embodiments, the needle is open-ended for insertion of a specialized instrument for such uses as biopsies and spectroscopic tissue analyses. These procedures can be conducted before or after hyperthermia treatment of the tissue by replacing fiber in the needle casing with such a specialized instrument or vice-versa. A particular application facilitates the use of laser-induced hyperthermia to treat benign prostatic hypertrophy.