Thymic Carcinoma with Overexpression of MutatedKITand the Response to Imatinib

Abstract

In April 2002, a 54-year-old man presented with thoracic pain and respiratory distress; a mediastinal mass, 7.7 by 6 cm, was found on positron-emission tomographic and computed tomographic scanning. Further examination showed elevated liver-enzyme levels and multiple liver metastases. Liver biopsy revealed metastatic, poorly differentiated epidermoid carcinoma of the thymus,¹ with strong KIT expression ( Figure 1 ). The patient started taking imatinib at a dose recommended for the treatment of gastrointestinal stromal tumors (400 mg per day).² Within one week, his pain and respiratory distress disappeared. His liver metastases shrank within four months, and his liver-enzyme levels normalized, while the mediastinal tumor showed stable disease.