[A case of small cell lung cancer associated with pulmonary sarcoidosis].

A 63-year-old man with pulmonary sarcoidosis, diagnosed by mediastinal lymph node biopsy in 1977, was admitted in Feb. 1987 because of shortness of breath and cough. Chest X-ray showed bilateral hilar lymphadenopathy and a tumor shadow in the right lung field. Histological examination of specimens biopsied from the right lung revealed small cell carcinoma (S.C.C.). Bronchoalveolar lavage was performed to evaluate the disease activity of sarcoidosis, and the total number of cells and T-lymphocytes; the ratio of CD4+ cells to CD8+ cells was not increased. He was treated with combination chemotherapy, however, he died of respiratory failure after 7 months. An autopsy was performed, and the lesions were examined histologically. The sarcoid lesion in a lymph node obtained at autopsy was not active, in contrast to that obtained by mediastinal lymph node biopsy. Lung cancer and sarcoidosis are both common diseases, but their coexistence in the same patient is not common, and autopsied cases are rare. In this case, an autopsy was performed, and BAL had been performed prior to his death. The relationship between the BAL findings and the histology of sarcoidosis was examined. Based on the results of autopsy and BAL, the sarcoidosis was inactive prior to death, but had been histologically active 10 years previously. Therefore, this is a very interesting case, since we can examine the relationship between the two diseases, and the progression of each disease. This case also provides an interesting example of differentiation of sarcoidosis from S.C.C. Metastatic invasion of the hilar lymph nodes without bronchial stenosis and changes secondary to stenosis may often occur in patients with small cell lung cancer. Such metastatic invasion closely resembles the bilateral hilar lymphadenopathy of sarcoidosis; therefore, in some cases, it may be extremely difficult to differentiate the two diseases.