Obtaining accurate temperature distributions in living tissue related to hyperthermia skin cancer treatment without using an intruding sensor is a challenge. Here, we report a mathematical model that can accurately determine the temperature distribution in the tumor region and surrounding normal tissue. The model is based on a modified Pennes' equation for the bioheat transfer in a 3-D triple-layered skin structure embedded with a vascular countercurrent network and a tumor appearing in the subcutaneous region. The vascular network is designed based on the constructal theory of multi-scale tree-shaped heat exchangers. The tumor is injected with gold nanoshells in order to be heated quickly. The proposed model is implemented numerically using a stable finite difference scheme. The method is demonstrated and tested by an example. (C) 2017 Elsevier Ltd. All rights reserved.