[An unusual tumor of the oral cavity in a fetus and prenatal ultrasonography--case report].

Objective: The tumours and pseudotumours of the foetal face are very rare diseases. Basic method for their prenatal diagnosis is ultrasound. The authors describe the case of diagnosed orofacial pseudotumour--sublingual cyst.

Design: Case report introduces some rules for ultrasound investigation of foetal face.

Setting: Department of Clinical Genetics and Foetal Medicine, University Hospital Olomouc.

Subject And Method: The cyst of oral cavity was diagnosed by ultrasound in second trimester of gestation. It was repeatedly punctured during pregnancy and the content was cytologically examined. Exstirpation was performed after delivery. Histological etiology--dysontogenetic cyst--was established.

Conclusion: Prenatal ultrasonographical diagnosis of the oral pseudotumour was completed by puncture procedures. This invasive way verifies anatomical conditions, enables histological investigation and warrants the swallowing act which is the prevention of polyhydramnion.