Thymoma exhibiting spontaneous regression in size, pleural effusion and serum cytokeratin fragment level: A case report

Abstract

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 11.0x6.0x5.0 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 (10.0x5.5x4.4 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 (9.5x5.4x4.2 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 (8.0x3.6x3.0 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. IntroductionThymoma is derived from thymic epithelial cells and is one of the most common neoplasms in the anterior mediastinum (1). The overall incidence of thymoma is 0.15 cases per 100,000 individuals and the majority of the patients with thymoma or thymic carcinoma are aged 40-60 years (2,3). The World Health Organisation (WHO) classification is based on histological analysis of epithelial cell atypia and the degree of infiltration of non-neoplastic lymphocytes (4). Although the great majority of these tumors exhibit more conventional histological characteristics, unusual types have also been described, such as sclerosing thymoma (5). Spontaneous regression (SR) of thymoma without therapy has been reported, although its incidence is rare (6)(7)(8). This is the case report of a patient with thymoma exhibiting SR and disappearance of the pleural effusion. Case reportA 30-year-old man was admitted to Toho University Omori Medical Center with right chest pain and low-grade fever. The patient was a never-smoker and had no medical history. On physical examination, the temperature was 37.8˚C and the respiratory sounds were clear. A chest X-ray revealed a mass shadow in the right hilum a...

Thymoma exhibiting spontaneous regression with developing myasthenia gravis: A case report

“…Ischemic infarction induces an inflammatory reaction presenting as pleural effusion, fever, and chest pain. [2][3][4] Here, thromboembolism was not observed, hence vascular occlusion caused by the rapid tumor enlargement resulted in ischemic infarction and inflammation. A relationship between multilocular cystic thymoma and inflammation has been reported.…”

“…Despite an aggressive subtype and large tumor size (median 65 mm, range 30-120 mm), thymomas exhibiting SR are diagnosed as early-stage tumors, specifically, Masaoka stage I or II. 3,4 Because such thymomas are surrounded by a thick capsule, tissue invasion does not occur. The tumor was mostly encapsulated; only the thymus microscopic invasion was found.…”

“…However, a thymoma exhibiting SR with elevated anti-AchR antibody was reported. 3,4 The thymus pathology examination was unremarkable. Of thymomas with MG, 65-90% have germinal centers, likely related to MG development in the thymus.…”

“…1 Thymomas rarely spontaneously regress. [2][3][4] Myasthenia gravis (MG), a common autoimmune disease, accounts for 20-30% of all thymomas and occurs as a paraneoplastic disorder. 5 We report a rare case of a thymoma undergoing spontaneous regression (SR) due to intratumoral infarction with MG.…”

Transcutaneous B-mode ultrasound (TUS) and contrast-enhanced ultrasound (CEUS) pattern of mediastinal tumors: a pictorial essay

“…Among the primary benign MTs located in the anterior mediastinum, regressive thymoma lesions ( Fig. 1 ) ( 1 , 3 , 12 ) , mediastinal cysts ( Fig. 2 ) ( 1 , 3 ) , mediastinal ectopic thyroid gland ( Fig.…”