Minimally invasive resection of a mediastinal teratoma with coexisting somatic-type adenocarcinoma.

Germ cell tumors (GCTs) of the anterior mediastinum are relatively uncommon, with mature teratomas being the most frequent subtype. Although typically benign, mature teratomas may rarely undergo somatic-type malignant transformation, significantly worsening prognosis and posing diagnostic challenges. We report a case of a young female presenting with chest heaviness and exertional dyspnea. Imaging revealed a well-defined anterior mediastinal mass suggestive of a mature teratoma. Thoracoscopic excision was performed, and the mass was found adherent to surrounding vital structures, including the lung, pericardium, and major vessels. Complete resection was achieved through meticulous adhesiolysis. Histopathological evaluation revealed a focus of somatic-type adenocarcinoma arising within a mature mediastinal teratoma, confirming malignant transformation. This case highlights the importance of thorough tissue sampling and histopathological evaluation, crucial for establishing the diagnosis. Given the rarity of such transformations, standardized treatment protocols remain undefined. This case underscores the diagnostic and therapeutic challenges associated with malignant transformation in mediastinal teratomas.