[Case of sarcoidosis with squamous cell carcinoma which originated from solitary bronchial papilloma].

A 60-year-old man was given a clinical diagnosis of sarcoidosis, with enlarged mediastinal and hilar lymphadenopathy by chest CT, high levels of angiotensin-converting enzyme, and gallium scintigraphy findings. After 2 years follow-up, chest CT showed that only the right superior lobe bronchial lymph node had enlarged, occluding the right B1 bronchus, but other enlarged lymph nodes had not changed in size. We performed bronchoscopy to evaluate the occlusion of the right B1 bronchus, and recognized a polypoid lesion. Transbronchial tumor biopsy specimens revealed squamous cell lung carcinoma. A right upper lobectomy and drainage of the hilar and mediastinal lymph regions were performed. Histopathological examination revealed the coexistence of squamous cell carcinoma with many non-caseating epithelioid cell granulomas in all hilar and mediastinal drainage lymph nodes, but no metastasis. Non-caseating epithelioid cell granulomas were also seen in the lung interstitium. Histopathological examination suggested that the squamous cell carcinoma originated from a solitary bronchial papilloma. A diagnosis of lung cancer complicated with sarcoidosis was difficult by clinical imaging alone, including FDG-PET/CT. This suggests the importance of bronchoscopic examination, if a clinical course of the disease appears to be different from the usual course. This was a rare case of squamous cell carcinoma which originated from a solitary bronchial papilloma.