Spontaneous regression of cancer is an extremely rare phenomenon, and it has been described in only a few cases of pulmonary cancer. We report a case of complete spontaneous regression of squamous-cell lung cancer (SCLC) following a core needle biopsy in a 67-year-old female patient with two previous lung cancers and concomitant follicular lymphoma. The patient was diagnosed with SCLC after 4 core needle biopsies from a nodule in the left upper lobe and at the same time suspected of having follicular lymphoma. Treatment for the lung cancer was delayed by approximately 8 weeks because the diagnosis of lymphoma was both challenging and time-consuming. A computed tomography scan was performed in relation to the scheduled treatment for SCLC, showing that the pulmonary nodule had disappeared completely. Most other cases of spontaneous regression of lung cancer hint at the involvement of immunological factors, and this case possibly involves a combination of mechanical and local immunological factors. Genetic and immunological analysis of patients showing spontaneous regression of cancers could provide valuable information.