A Case of Vanishing Thymoma

Cystic thymoma is a rare clinicopathologic entity. Chronic inflammation within and around these tumors has been suggested to compromise the vascular supply, leading to hemorrhage into the lesion and necrosis. This can result in rapid expansion of the tumor and symptoms owing to local compression. We present the case of a patient with a biopsy-proven lymphocytic-predominant thymoma who underwent resection to reveal a hemorrhagic, necrotic mediastinal cyst adjacent to a focus of organizing pneumonia, with no residual thymoma.