A Case of Primary Pulmonary Lymphoepithelioma-like Carcinoma Misdiagnosed as Adenocarcinoma
A 60-year-old woman visited our outpatient clinic for evaluation of a lung mass incidentally detected on chest computed tomography (CT) during regular medical check-up. Physical and laboratory examination did not reveal any relevant abnormalities. She had no medical illness and was never-smoked. Initial chest radiograph revealed a nodular opacity in the right middle lung field (). On chest CT, there was an approximately 3.1 cm mass in diameter with spiculated margin and heterogeneous enhancement in the right lower lobe of the lung, which invaded right major fissure. In addition, there were adjacent ground-grass opacities posterior to the mass (). Next, we performed PTNB for the histological diagnosis for the mass. Microscopic examination showed that tumor cells were arranged in diffuse pattern and reveal round nuclei without prominent nucleoli and moderate amount of cytoplasm. The tumor cells were diffusely stained with p53, thyroid transcription factor-1, and Ki-67 on immunohistochemical analysis, suggesting that it was a malignant mass such as poorly differentiated adenocarcinoma. As for the staging work-up, positron emission tomography-CT and brain magnetic resonance revealed that the mass was hypermetabolic (standardized uptake value, 9.32) with high uptake of fluorodeoxyglucose () and that there was no metastatic foci or lymphadenopathies, altogether, it was diagnosed as adenocarcinoma of cT2aN0M0 (stage IB) by TNM staging system. For her treatment, she underwent the right lower lobectomy. On histological examination, the tumor was grossly 1.8×1.5 cm-sized and ashen gray-colored mass with ill-defined margin. The mass was firm to palpation without pleural, vascular, and lymphatic invasion. It was composed of large epithelioid malignant cells with undifferentiated appearance, syncytial growth, and adjacent reactive lymphoplasmacytic cells influx (). Moreover, some of the malignant cells were positive for in situ hybridization with EBV-coded small RNA (EBER) (). Any glandular and squamous cell differentiation was not detected. Based on these histologic findings, the mass was finally diagnosed as primary pulmonary LELC of pT1aN0M0 (stage IA). After the surgical resection, there had been no recurrence or complication of disease at follow-up of 3 years.