Benign giant mediastinal schwannoma presenting as cardiac tamponade in a woman: a case report.

INTRODUCTION: Mediastinal schwannomas are typically benign and asymptomatic, and generally present no immediate risks. We encountered a rare case of a giant benign posterior mediastinal schwannoma, complicated by life-threatening cardiac tamponade. CASE PRESENTATION: We report the case of a 72-year-old Japanese woman, who presented with cardiogenic shock. Computed tomography of the chest revealed a posterior mediastinal mass 150 cm in diameter, with pericardial effusion. The cardiac tamponade was treated with prompt pericardial fluid drainage. A biopsy was taken from the mass, and after histological examination, it was diagnosed as a benign schwannoma, a well-encapsulated non-infiltrating tumor, originating from the intrathoracic vagus nerve. It was successfully excised, restoring normal cardiac function. CONCLUSION: Our case suggests that giant mediastinal schwannomas, although generally benign and asymptomatic, should be excised upon discovery to prevent the development of life-threatening cardiopulmonary complications.

Zeta-sarcoglycan is a functional homologue of gamma-sarcoglycan in the formation of the sarcoglycan complex.

The sarcoglycans (SGs), transmembrane components of the dystrophin-associated glycoprotein complex, are stable and functional only when they assemble into a tetrameric complex in muscle cells. A defect in any one of the four SG members disrupts the entire SG complex (SGC) and causes limb-girdle muscular dystrophy. zeta-SG has been recently found as a transmembrane protein homologous to gamma-SG and delta-SG. To characterize zeta-SG in complex formation, we co-transfected expression vectors encoding all six SGs (alpha-, beta-, gamma-, delta-, epsilon- and zeta-SG) and dystroglycan into Chinese hamster ovary cells. Immunoprecipitation analysis showed that zeta-SG or gamma-SG formed a SGC with beta-SG and delta-SG plus alpha-SG or epsilon-SG, revealing that zeta-SG can form two types of SGCs (alpha-beta-zeta-delta or epsilon-beta-zeta-delta). This result indicates the functional resemblance of zeta-SG to gamma-SG rather than delta-SG, although phylogenetic analysis suggests that zeta-SG is evolutionally closer to delta-SG than to gamma-SG. Reverse transcription (RT)-PCR showed that the expression pattern of the transcript was almost the reciprocal of that of gamma-SG in various mouse tissues and that the zeta-SG transcript was especially abundant in the brain, suggesting that zeta-SG might play a particular role in the central nervous system.