Histological examination and immunohistochemical features of the tumor. (A) The tumor shows irregularly connected strands forms a “Dog-like” structure in a dense fibrous tissue with scattered individual or groups of fat cells (H&E staining, ×40). (B) Sparse lymphocytes are infiltrated in the slender elongate epithelial strands and in some area, thymic corpuscle can be observed (H&E staining, ×100). (C) The epithelial strands of the tumor are positive for CK19 (Envision×100). (D) Lymphocytes are immunostained by CD3 (Envision×100).