title: Thymoma exhibiting spontaneous regression in size, pleural effusion and serum cytokeratin fragment level: A case report.
abstract: A 30-year-old man was admitted to Toho University Omori Medical Center for assessment of right chest pain and fever. Chest computed tomography (CT) revealed an anterior mediastinal tumor sized 11.0×6.0×5.0 cm, with right pleural effusion. The laboratory analysis revealed elevated white blood cell count (11,000/µl), C-reactive protein (4.1 mg/dl) and cytokeratin fragment (CYFRA; 12.7 ng/ml; normal, <2 ng/ml). The level of CYFRA in the pleural effusion was also markedly elevated (143 ng/ml). On the first day after admission (6 days after the initial CT), there was a mild regression on CT (10.0×5.5×4.4 cm; reduction rate, 26.7%), with decrease of the pleural effusion volume. A CT-guided needle biopsy was performed, but the findings were not conclusive, as most of the tissue was necrotic. Seven days later (13 days after the initial CT), a CT revealed further regression (9.5×5.4×4.2 cm; reduction rate, 34.7%) with disappearance of the pleural effusion. The patient was followed up on an outpatient basis. At 35 days after the initial CT, the tumor continued to shrink without treatment (8.0×3.6×3.0 cm; reduction rate, 73.8%) and the serum CYFRA level had decreased to 0.8 ng/ml, although it had not returned to normal levels. At 62 days after the initial CT, the patient underwent surgical resection. The resected specimen was diagnosed as thymoma (World Health Organization type B2; Masaoka classification, stage II), with prominent degeneration and necrosis. One possible cause of the spontaneous regression may be increased internal pressure, probably associated with rapid tumor growth, leading to massive necrosis with resulting chest pain, inflammatory reaction with pleural effusion and subsequent tumor regression. The serum CYFRA level may be a useful marker for the evaluation of the clinical course of thymoma with extensive necrosis.
authors.affiliation: Division of Respiratory Medicine, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Furuya
authors.affiliation: Division of Respiratory Medicine, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Isobe
authors.affiliation: Division of Respiratory Medicine, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: G O
authors.initials: GO
authors.lastname: Sano
authors.affiliation: Division of Respiratory Medicine, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Kyohei
authors.initials: K
authors.lastname: Kaburaki
authors.affiliation: Division of Respiratory Medicine, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Gocho
authors.affiliation: Division of Respiratory Medicine, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Ishida
authors.affiliation: Division of Respiratory Medicine, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Naoshi
authors.initials: N
authors.lastname: Kikuchi
authors.affiliation: Division of Respiratory Medicine, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Keishi
authors.initials: K
authors.lastname: Sugino
authors.affiliation: Division of Respiratory Medicine, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Sakamoto
authors.affiliation: Division of Respiratory Medicine, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Yujiro
authors.initials: Y
authors.lastname: Takai
authors.affiliation: Division of Thoracic Surgery, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Otsuka
authors.affiliation: Division of Thoracic Surgery, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Hata
authors.affiliation: Division of Thoracic Surgery, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Iyoda
authors.affiliation: Department of Surgical Pathology, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Wakayama
authors.affiliation: Department of Surgical Pathology, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Shibuya
authors.affiliation: Division of Respiratory Medicine, Faculty of Medicine, Toho University Omori Medical Center, Tokyo 143-8541, Japan.
authors.forename: Sakae
authors.initials: S
authors.lastname: Homma
keywords: cytokeratin fragment; necrosis; pleural effusion; spontaneous regression; thymoma