Synchronous lung adenocarcinoma and intrapulmonary thymoma: A rare entity

OBJECTIVE: Primary intrapulmonary thymomas are very rare epithelial tumors below the visceral pleura or entirely circumscribed by lung parenchyma without evidence of a thymic lesion in the anterosuperior mediastinum, which display the characteristic histological features of thymomas. We present a case of a female patient presenting a synchronous in situ lung adenocarcinoma on the right and an intrapulmonary thymoma on the left side. CASE: A 52 year old woman suffering from myasthenia gravis, thymectomized 15 yrs earlier under treatment with Mestinon, otherwise asymptomatic was admitted to our hospital for a follow up examination. The histology 15 years earlier revealed thymic hyperplasia. The chest CT scan showed a small asymmetric lesion in the right upper lobe suspicious for lung cancer and a round lesion of 2X3cm in the left lower lobe suspicious for metastatic disease. F-fluorodeoxyglucose positron emission tomography that followed, had only a low uptake in both lesions. The patient was submitted to surgery, both lesions were excised with atypical resections and histology revealed in situ lung adenocarcinoma on the right lung and an intrapulmonary thymoma on the left one. The postoperative course was uneventful and the patient is disease-free for both pathologies followed by an oncologist and a neurologist 3 years later. CONCLUSION: Primary intrapulmonary thymoma (PIT), which is an intrapulmonary tumor without an associated mediastinal component, is rare and a slow-growing tumor that may respond well to surgical resection when confined to the lung. The co-existence of an in situ adenocarcinoma of the other lung is a strange coincidence not described ever in the literature.