Jpn J Clin Oncol1998;28(6)405-409 Primary Unknown Cancer in Pulmonary Hilar Lymph Node with Spontaneous Transient Regression: Report of a Case

A 69-year-old man was referred to our hospital in December 1993because an abnormal mass hadbeendetected inthe rightpulmonary hilum. Computed tomography (CT) ofthechestrevealed a swollen hilar lymph node between the right middle and lower lobe bronchi, and an adherent tumor in the rightventrobasal segment (S8). Chest roentgenogram in February 1994, however, showed no evident tumor in the right lung field. In March 1996, the mass in the rightpulmonary hilum reappeared on chest roentgenogram. Chest CT revealed a swollen hilar lymph node between the right middle and lowerlobebronchi, but there was no tumor in right S8.The patient underwent video-assisted thoracoscopy on 17 May 1996. Intraoperative needle biopsy of the node revealed cancercells. We performed right middle and lowerbilobectomy with mediastinal dissection. Histological diagnosis revealed a large cell carcinoma almostcompletely occupying a hilar lymph node. The resected middle and lower lobes showed no tumors, except for a coagulation necrosis measuring 1.5 cm in diameter in S8b, corresponding to the site where a tumor shadow had been depicted on the CT image in December 1993. We concluded that the coagulation necrosis might have been the primary site of the tumor, which had spontaneously regressed and then appeared in the metastatic interlobar node