Ectopic Cervical Thymoma: A Case Report and Review

Abstract

In the embryo, the thymus originates from the third and fourth pharyngeal pouches and migrates from the superior neck to the mediastinum. Ectopic cervical thymoma (ECT) is an extremely rare tumor that originates from ectopic tissue, and is caused by the aberrant migration of the embryonic thymus. Our patient was a 30-year-old woman who had a nodular lesion in the neck for several years. Ultrasonography and computed tomography were performed. She underwent surgery, and a histological examination resulted in a diagnosis of type AB thymoma. Herein, we report a case of ECT that was resected through a transcervical approach.

Keywords: Ectopic; Thymectomy; Thymoma.

Fig. 1

(A) An axial CT image shows a slightly enhanced large oval mass in the left neck. (B) A coronary CT image shows cervical trachea deviation to the right due to compression by the well-capsulated tumor with smooth contour in the lower pole of the left thyroid gland. The mass contains septa (black arrow). CT, computed tomography.

Fig. 2

The resected tumor exhibits a lobulated and lemon-yellow-colored cut surface. The specimen has an internal lobulated architecture separated by fibrous septa.

Fig. 3

(A) Microscopic findings. The tumor is composed of a lymphocyte-poor type A area and a lymphocyte-rich type B-like area. The 2 components are separated by fibrous septa (H&E, ×200). Immunohistochemically, (B) the type A area is composed of spindle cells and few TdT-positive immature T cells, but the type B-like area contains many TdT-positive T cells and round or polygonal tumor cells with indistinct nucleoli (×200). (C) CK-19 staining shows aggregates of epithelial cells in the type A area and a dense epithelial network with many CK-19-negative lymphocytes in the type B-like area (×200). TdT, terminal deoxynucleotidyl transferase; CK, cytokeratin.