Fourteen cases of spindle cell
thymoma with prominent desmoplastic changes are presented. The patients are 9 women and 5 men between the ages of 46 and 79 years. Clinically, the patients presented with symptoms of
chest pain,
shortness of breath, and
dyspnea. Radiographic imaging showed the presence of an anterior mediastinal mass, and surgical resection of the
tumor mass was accomplished in all of the cases. Grossly, all the
tumors were described as ovoid
tumor masses measuring between 4 and 9 cm in greatest dimension. At cut surface, the
tumors were described as solid and light tan-brown in color.
Necrosis and
hemorrhage were not recorded in any of the cases. Histologically, 8 cases were invasive, and 6 were encapsulated
tumors. Extensive areas of young fibrocollagen and a prominent fibroblastic proliferation characterized the
tumors. Scattered areas of more conventional spindle cell
thymoma were present in all cases but mitotic activity,
necrosis, and/or
hemorrhage were not identified. Immunohistochemical stains were performed in 9 cases, showing
tumor cells positive for pancytokeratin,
cytokeratin 5/6, Bcl-2, Pax8, and
vimentin. Clinical follow-up in 8 patients showed that all are alive and well 1 to 8 years after diagnosis. The current growth pattern of spindle cell
thymomas is unusual and should be kept in mind when evaluating mediastinoscopic biopsies.