Small cell lung cancer mimicking a pulmonary venous angiosarcoma.

A 67-year-old man presented with dyspnoea and non-specific chest pain. A CT scan showed a mass lesion within the right superior pulmonary vein protruding into the left atrium (fig 1A, B). Positron emission tomography with fluoro-2-deoxy-Dglucose showed uptake within the lesion but no extrathoracic disease (fig 1C). A clinical-radiological diagnosis of pulmonary venous angiosarcoma was made and surgical resection was offered for symptom palliation. At surgery the tumour mass was found to be growing from the right superior pulmonary vein into the left atrium (fig 2A). No lung mass was seen intraoperatively. A right pneumonectomy with en bloc resection of the left atrium and posterior wall of the right atrium was performed in order to achieve clear resection margins. Unexpectedly, histological examination showed small cell lung cancer and microscopic examination revealed a tiny focus of tumour within the adjacent lung parenchyma. The tumour had grown into the pulmonary vein and then extended along it into the left atrium (fig 2B). The pathological staging was pT4 pN0 pMx. The patient recovered well from surgery and received four cycles of adjuvant chemotherapy postoperatively. Invasion of the atria by carcinoma of the lung is uncommon and usually occurs by direct invasion. Although there are reports of lung cancer growing into the left atrium via the pulmonary veins, there is usually an obvious parenchymal lung mass. This case is unusual in that the tumour had arisen from a small focus within the lung parenchyma adjacent to the vein and then grown within the vein, mimicking an angiosarcoma. Surgery for angiosarcoma can produce an acceptable survival rate with palliation of symptoms. However, had a preoperative diagnosis of small cell lung cancer been possible, this patient would have been offered primary chemotherapy. He did, however, achieve excellent palliation of symptoms with surgery.