A CASE OF HUGE RETROPERITONEAL ANCIENT SCHWANNOMA DEFYING DIAGNOSIS

A 47-year-old asymptomatic man visited a near by hospital for a routine physical examination. A huge abdominal tumor as large as infant's head sized was detected, and he was admitted to our hospital for further examination and treatment. After several examinations, the tumor was identified as a retroperitoneal multicystic tumor, but no definite diagnosis could be made. The tumor was in contact with pancreas, left adrenal and left kidney but was easily removed without resecting other organs. The resected specimen was 19cm in diameter and weighed 1950g. Histopathologically, Antoni A and B regions were observed and a ganglion was noted adjacent to the tumor. Immunologically, S-100 protein stained positive and ultimately the tumor was diagnosed as an ancient schwannoma. Retroperitoneal ancient schwannomas are rare and the lesion in this case was the largest found in a review of the literature.