Giant mediastinal mature teratoma with increased exocrine pancreatic activity presenting in a young woman: a case report
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Mediastinal mature teratoma is a benign, slow-growing tumor typically affecting 20- to 40-year-old adults. Fluid examination from the cystic masses rarely shows enzymatic activity as we describe in this report.
We report a case of a giant mediastinal germ cell tumor (measuring 15 cm × 14 cm × 8 cm) detected in a 35-year-old Caucasian woman. Microscopic examination showed that the lesion resembled a mature cystic teratoma with areas of pancreatic tissue with mature ductal and acinar structures intermixed with islets of Langerhans. Fluid from the cysts in the mass was examined after removal showed amylase activity of 599 U/l despite normal serum levels. The post-operative period was free of complications, and the patient was discharged on post-operative day 10.
Complete surgical removal is the treatment of choice for mature cystic teratomas, with optimal results and acceptable surgical risk. Exocrine pancreatic function may be an aid to pre-operative or intra-operative diagnosis; however, these findings have no impact on survival or the therapeutic pathway.
KeywordsTeratoma Germ Cell Tumor Mature Teratoma Exocrine Pancreatic Function Mature Cystic Teratoma
Primary germ cell tumors (GCTs) of the mediastinum are rare tumors (10% to 15% of all mediastinal tumors), and they usually appear during the third to fourth decade of life . GCTs are predominantly found in gonads, and the anterior mediastinum is the common extragonadal site . The majority of mediastinal teratomas are mature teratomas that are histologically well-defined and benign . Malignant GCTs account for less than 1% of all mediastinal tumors, and mature teratomas account for approximately 8% .
Once the mediastinal cavity was opened, it was possible to see the presence of the voluminous tumor, which occupied most of the right hemithorax with compression of the adjacent pulmonary parenchyma. There were also widespread adhesions to the superior vena cava, the ascending aorta, the pericardium, and part of the lower pulmonary lobe, where an atypical resection of pulmonary parenchyma was performed.
The lesion measured 15 cm × 14 cm × 8 cm and showed smooth, regular external contours. The cut surface of the mass was cystic, filled with a yellowish white proteinaceous material admixed with hair. A thickened area of the cyst wall measuring 6.5 cm across was composed of a more solid white fibrous tissue, which also contained multiple small cysts filled with yellowish material. Fluid from the cysts in the mass was examined after removal, showing an amylase activity of 599 U/l despite serum levels being normal.
Mature teratomas typically occur in young patients (mean age, 27 years), with approximately equal frequency in men and women (> 90% of malignant germ cell tumors occur in men). Histologic examination of mature teratomas reveals malignant transformation in less than 1% of cases and is usually characterized by the malignant degeneration of the squamous epithelium . Although the actual mechanism of development is unclear, it is believed that these lesions consist of primordial germ cells which stray into midline extragonadal areas in the migration during embryonic development . Most patients with germ cell tumors in the mediastinum are asymptomatic, so these neoplasms are usually discovered by accident during routine chest X-ray examinations . Patients may present with chest, back, or shoulder pain; dyspnea; fever; pleural effusion; cough; and bulging of the chest wall. Less commonly, tumors become infected or may rupture into adjacent organs, such as the lung, bronchial tree, or pleural and pericardial space [2, 5]. Symptoms can also derive from the pressure exerted on the surrounding tissue (vena cava syndrome), and occasionally fluid examination from the cystic mass shows physiological activity. Some authors [6, 7] have suggested that exocrine secretion by pancreatic tissue and leakage of digestive enzymes from intestinal or salivary tissue are due to non-infective inflammation around the mass. Others  believe that exocrine pancreatic function may be an aid to pre-operative or intra-operative diagnosis. Anyway, these findings have not had an impact on survival or on the therapeutic pathway. For cases of pure mature cystic teratomas, complete surgical removal alone is the treatment of choice, with optimal results and acceptable operative risk.
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