The patient was a 71-year-old man who underwent left upper lobectomy for left lung cancer 4.5 years previously. During follow-up period, a shadow in the right upper lobe of lung which enlarged with time appeared and lung carcinoma was suspected. Preoperative contrast-enhanced CT scan revealed partial anomalous pulmonary venous connection (PAPVC) where the V1+2+3 had drained into the superior vena cava. Since his PAPVC was present in the lung lobe to be resected, he was asymptomatic, and the pulmonary blood flow/systemic blood flow ratio (Qp/Qs) was 1.7, we considered the lesion to be within the allowable range for surgery. We thus decided to employ surgical diagnosis and treatment. We performed thoracoscopic right upper lobectomy. The patient required some respiratory rehabilitation after the operation. He was discharged from our hospital on the 13^th postoperative day. Cardiac ultrasonography performed after the operation revealed the decreased Qp/Qs to 1.1, revealing improved right cardiac load-carrying capacity.

We have experienced a resected case of right upper lobe carcinoma associated with PAPVC in the same lobe after left upper lobectomy. Although PAPVC is a comparatively rare congenital anomaly, it can cause right heart failure after surgery if it is present in the non-resected lung lobe. In performing lung resection, we must make preoperative imaging diagnosis by baring a possible existence of PAPVC in mind.