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

Thymoma Exhibiting Spontaneous Regression With Cystic Change Due to Acute Infarction: A Case Report and Literature Review

Spontaneous regression (SR) of thymoma is rare. We report a case of a surgically resected thymoma due to cystic changes owing to acute ischemic infarction with an increased anti-acetylcholine receptor antibody level. A 61-year-old male underwent a computed tomography (CT) scan, which showed a 4.9 cm anterior mediastinal tumor and slight right pleural effusion. Blood test results indicated an elevated white blood cell count of 13300/mL. One month later, an enhanced CT scan at our hospital showed spontaneous mediastinal tumor regression to 3.7 cm and no pleural effusion. The tumor contained homogeneous low-density areas on enhanced CT, which showed high intensity on T2-weighted magnetic resonance imaging, indicating cystic changes. He had no symptoms of myasthenia; however, his anti-acetylcholine receptor antibody level was slightly elevated (0.4 nmol/L). Suspecting a thymoma, an extended total thymectomy through a median sternotomy was performed. Histopathological analysis confirmed the diagnosis of thymoma type B2 and Masaoka stage I. SR is due to acute intratumoral infarction. At two years postoperatively, no tumor recurrence or development of myasthenia gravis was observed. Thymomas should be included in the differential diagnosis of anterior mediastinal tumors that regress spontaneously with cystic changes, pleural effusion, and an elevated inflammatory response. Mature cystic teratoma rupture should be differentiated, but preoperative biopsy is often challenging owing to necrotic and fibrous tissues; therefore, early surgical resection is required for diagnosis and treatment.

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

Spontaneous regression (SR) of thymoma is rare. A 44-year-old man with right chest pain underwent computed tomography (CT), which showed an 11.0 cm mass in the anterior mediastinum and right pleural effusion. He refused surgery and was sent home without medication and additional treatment. One year later, the mass had regressed to 5.5 cm, and the right pleural effusion had disappeared. He was then lost to follow-up. Four years after the initial visit, he presented with diplopia and fatigue. A significant increase in his anti-acetylcholine receptor antibody levels led to myasthenia gravis (MG) diagnosis. CT revealed a regressed mediastinal mass (3.0 cm). After extended thymectomy, histologic analysis confirmed a thymoma type B2, Masaoka stage IIa. The SR was due to intratumoral infarction. This report is the first to describe MG developing during SR. Anterior mediastinal tumors undergoing SR should be differentiated from thymomas and MG perioperative development should be considered.

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

Sound reflection from bony structures and from air-filled lung parenchyma limits transcutaneous B-mode thoracic ultrasound of the mediastinum. Computed tomography and magnetic resonance imaging of the thorax are the primary overview imaging modalities for mediastinal pathologies. However, pathological processes originating from the mediastinum can be sonographically visualized and evaluated in the presence of displacing or infiltrative growth. The aim of this pictorial essay is to demonstrate contrast-enhanced ultrasound as a method complementing B-mode ultrasound, computed tomography, and magnetic resonance imaging for the evaluation of mediastinal tumors, taking into account the clinical background. The characteristic perfusion patterns of mediastinal pathology are presented.