Abstract
Background : Primary retroperitoneal mucinous cystic tumors are rare. We report the cytology and histology of a case and discuss its differential diagnostics points.
Case : A woman in her twenties reporting right abdominal pain and found in ultrasonograms and computer tomography to have a cystic tumor beneath the right kidney had no epithelial cells aspirated in percutaneous fine needle aspiration cytology done three times and yielding only sticky fluid. Cytological preparations from the fluid in a surgically resected cyst yielded many tall columnar cells forming numerous clusters arranged in sheets or papillary patterns. Nuclear atypia were insufficient for carcinoma diagnosis. The resected cystic 5×5 cm tumor contained dark brown mucinous fluid. Microscopically, it was diagnosed as a primary retroperitoneal mucinous tumor of low malignant potential. Immunohistochemical examination revealed ovarian stroma cells in tumor stroma.
Conclusion : It is important to suspect a primary retroperitoneal mucinous tumor when an aspiration biopsy cytology specimen from a retroperitoneal cystic lesion contains mucinous material, even if no epithelial cells are seen.
