[A case of primary lung cancer with swollen mediastinal lymph nodes due to pre-existing sarcoidosis].

A 69-year-old man, who had been followed up for sarcoidosis at another hospital from 10 years previously, was referred to our hospital because of a new lesion in the left upper lobe. A chest CT scan revealed a nodular lesion at the orifice of the left B3b and mediastinal lymphadenopathy. Bronchoscopic biopsy established a diagnosis of squamous cell carcinoma. Because there had been no distant metastasis and no change in size of the mediastinal lymph nodes over the previous 5 years, left upper lobectomy with lymph node dissection was performed. The histology of the resected tumor indicated a moderately-differentiated squamous cell carcinoma, and the dissected lymph nodes contained non-caseous epithelioid cell granuloma without metastasis. Thus, we made a final diagnosis of squamous cell carcinoma (pT1N0M0, stage IA) that complicated the sarcoidosis. Surgical resection can be the first option for lung cancer complicating sarcoidosis with mediastinal lymphadenopathy, because making a preoperative assessment of N status is difficult.