Clinicopathological features of type AB thymoma with liver metastases.

OBJECTIVE We studied the clinicopathological features of type AB thymoma with liver metastases and explore the histological types, diagnosis and differential diagnosis, treatment and prognosis for this disease. METHODS Liver metastasis specimens were derived from one case of type AB thymoma 5 years after operation and were examined histologically using light microscopy and immunohistochemistry. A comprehensive analysis was performed on the patient's clinical manifestations, histopathology, immunohistochemistry features, differential diagnosis, treatment and prognosis in combination with a review of the relevant literature. RESULTS Metastases were detected 5 years after initial operation on a 49-year-old, female patient with type AB thymoma. The pathological diagnosis for the liver metastases was type AB thymoma. Immunohistochemistry staining showed CKpan (+), CD3 (+), CD2 (+), TdT (+), CD5 (+), P53 (+), Hep-1 (-), and Ki67-positive cells (25%). The expression level of galectin-3 was higher than in the mediastinal thymoma tissue identified 5 years prior. CONCLUSION Liver metastases of type AB thymoma are extremely rare. This case indicated that type AB thymoma with low malignant potential might recur and develop distant metastases. Overexpression of p53, galectin-3 and Ki67 in type AB thymoma might coordinately manipulate the process of development, progression and malignant transformation of type AB thymomas.