Simultaneous adenocarcinoma and squamous cell carcinoma arising from a mediastinal cystic teratoma: Case report and literature review

Teratoma with malignant transformation is rarely seen in gonadal or extra-gonadal sites. Extra-gonadal teratoma with malignant transformation is usually found in the mediastinum. More than two-thirds of mediastinal teratoma with malignant transformation cases receive chemotherapy or irradiation at the time of diagnosis. Herein, we report a naturally occurring mediastinal teratoma with malignant transformation in a 43-year-old man complaining of chest tightness and severe dyspnea. A huge cystic mediastinal mass was discovered from chest-computerized tomography scan. Emergent thoracostomy was performed to remove the tumor because of impending respiratory failure. The histology of the tumor was compatible with cystic teratoma, and the transformed non-germ cell region showed both adenocarcinoma and squamous cell carcinoma. The patient underwent postoperative chemotherapy. However, his condition deteriorated rapidly and he expired 8 months after diagnosis. Summarizing previous case reports in the literature: (1) 34.6% of mediastinal teratoma with malignant transformation patients survive after treatment; (2) the malignant components are sarcoma and carcinoma; similar survival rates are achieved where both histological features are present, however, survival is reduced with multiple or mixed types of malignant transformation; (3) the delineation between treatment-induced and naturally occurring teratoma with malignant transformation at the mediastinal site is indistinct; and, (4) complete surgical eradication is still the mainstay of treatment for prolonged survival in patients with mediastinal teratoma with malignant transformation.