Necrotic Thymoma Discovered Due to Subjective Symptoms: A Report of Three Cases

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INTRODUCTION: Thymomas are solid tumors that usually grow slowly and rarely cause symptoms or spontaneously regression. We have observed three cases of thymoma in which the patient presented with fever and chest pain, and pathological examination showed relatively extensive necrosis. The tumors spontaneously shrank during the course of the diseases.

CASE PRESENTATION: The patients, of a 30-year-old man, 46-year-old man, and 76-year-old man presented with fever and/or chest pain, and blood tests showed high levels of inflammation. Contrast-enhanced chest computed tomography (CT) showed masses with low-density area and contrast-enhanced margins. Two patients had repeat chest CT just prior to surgery, and the tumors had shrunk. In all cases, the masses were removed by a median sternotomy. The mediastinum tissue was hard due to inflammation, and in all cases the tumors were adherent to the lungs and in one case wedge resection of the left lung was required. Histopathological examination revealed extensive necrosis of the tumors, and based on residual viable tumor cells, the three tumors were diagnosed as follows respectively; type B2, type B2 with some type B3 components, and type AB thymoma. All tumors were classified as pT1aN0M0, Stage I, and Masaoka stage II.

CONCLUSIONS: Necrotic thymoma is associated with inflammation and spontaneous regression may be observed during the course of the disease. Since necrosis can be extensive, pathological examination should be performed throughout.