Cytologic findings in an effusion caused by rupture of a benign cystic teratoma of the mediastinum into a serous cavity.

Benign cystic teratomas of the ovary and anterior mediastinum are rarely complicated by rupture into an adjacent body cavity. Such rupture, however, is usually associated with life-threatening serositis and effusion. This report presents the cytologic findings in such an effusion, which in this case followed traumatic rupture of an anterior mediastinal benign cystic teratoma into a pleural space. Close examination of the cytologic preparations of the effusion showed the presence of squamous and columnar epithelial cells, anucleated squames, hairs, calcospherites (calcium deposits), keratinous material and cholesterol against an inflammatory background. These findings in an effusion from a patient presenting with acute respiratory distress or acute abdominal pain, while not absolutely diagnostic, should strongly suggest the possibility of a ruptured benign cystic teratoma.