A very rare case of spontaneous regression of basaloid squamous cell carcinoma of the lung

Abstract Spontaneous regression of non‐small cell lung cancer is relatively rare. Here, we present a very rare case of spontaneous regression of lung cancer which occurred in a patient with basaloid squamous cell lung cancer. To the best of our knowledge, this is the first report of such a case. A 76‐year old man was referred to our hospital with nodules in the right upper lobe determined by chest computed tomography. The nodules spontaneously regressed during follow‐up. Two years later, the tumor had regrown and the patient subsequently underwent surgery. The pathological findings showed basaloid squamous cell carcinoma. Stimulation of the immune system was considered to be the cause of the spontaneous regression and CD‐8 positive and CD‐4 positive lymphocytes might play an important role.