Small Cell Lung Cancer with Sarcoidosis in Spontaneous Remission: A Case Report

: A 69-year-old woman was diagnosed with sarcoidosis, which was not treated with corticosteroid therapy. Her levels of angiotensin converting enzyme decreased significantly over 4 years and a mass lesion was detected near the lower part of her left main bronchus, and diagnosed as small cell lung cancer (SCLC). Treatment of the SCLC with a series of chemotherapeutic agents produced excellent results. The pulmonary sarcoidosis did not show any deterioration despite the frequent use of amrubicin, which is known to be a cause of interstitial pneumonia. This is a case report of SCLC complicated with sarcoidosis in a stage of spontaneous remission, possibly suggesting an association between sarcoidosis and tumor immunity, since recent reports have suggested that immune checkpoint inhibitors might be involved in the development of sarcoidosis.