Thymic adenocarcinoma accompanied by type A thymoma and pulmonary minimally invasive adenocarcinoma and harboring distinct gene alterations

Abstract

Rationale: Thymic adenocarcinoma is an extremely rare thymic carcinoma. The exact genetic alteration associated with thymic adenocarcinoma is unclear. Here, we report a case of thymic adenocarcinoma accompanied by type A thymoma and pulmonary minimally invasive adenocarcinoma (MIA). Patient concerns: A 53-year-old woman presented with multiple nodules in the mediastinum and lung. Thoracic computed tomography revealed nodules in the anterior superior mediastinum and anterior mediastinum near the right pericardium and ground-glass opacity (GGO) in the right superior lobe of the lung. Diagnosis: The tumor in the anterior superior mediastinum was diagnosed as primary thymic papillary adenocarcinoma. The tumor in the anterior mediastinum near the right pericardium was diagnosed as type A thymoma. The GGO of the right superior lobe of the lung was diagnosed as a MIA. Intervention: The patient underwent thoracoscopic mediastinal tumor resection and partial lobectomy in our hospital. Outcomes: The postoperative course was uneventful. The patient is alive and free of the disease for 22 months after diagnosis. Lessons: Thyroid transcription factor 1 (TTF-1) was positive in this case of thymic adenocarcinoma, which indicated that a thymic adenocarcinoma with TTF-1-positive may not necessarily be a metastasis of lung or thyroid adenocarcinoma. The positive staining of CD5 and CD117 can help us to confirm the thymic origin. Molecular genetic analysis indicated that these tumors harbored different mutations. The thymic adenocarcinoma and type A thymoma both had the mutation of KMT2A , but the mutation sites were different. KMT2A mutation may be a common genetic change in thymic tumorigenesis. The genetic alterations disclosed in this study will help expand the understanding of thymic tumors.

The Role of Gene Fusions in Thymic Epithelial Tumors

“…These tumors had the typical morphology of B2 or B3 thymomas except for one case that also showed foci of thymic carcinoma. Interestingly, a KMT2A mutation has also been identified in a thymic papillary adenocarcinoma that occurred synchronously with a type A thymoma [33]. This 53 year-old woman presented with three nodules in the thorax including a 3 cm papillary adenocarcinoma in the anterior superior mediastinum, a 4 cm type A thymoma in the anterior mediastinum near the pericardium and a minimally invasive adenocarcinoma in the right upper lobe lung.…”