Fetiform teratoma: a rare cause of retroperitoneal mass: A case report

Fetiform teratoma is a rare highly developed mature teratoma with organoid differentiation although it is not as developed as fetus in fetus which is the only differential diagnosis of this entity. It should be distinguished from the fetus in fetu by absence of the axial skeleton. However, there is controversy in the distinction between Fetus in Fetu and fetiform teratoma and that both entities could represent two aspects of the same pathology at different stages of maturation. A day 6 female child with abdominal massunderwent ultrasonography, CT-scan and surgery.On imaging, Large well defined solid cystic lesion with soft tissue and macrocalcification in retroperitoneum in right side displacing right kidney to left side suggestive of Retroperitoneal Teratoma.. The entire sac with its content were completely excised. Tumor markers wasAFP >2000ng/ml, BHCG =15IU/L. The patient underwent surgery and The mass was excised in toto and observed having three distinct fetal heads with hair and clumped trunks.Very few cases of fetiform teratoma have been reported in English literature, however Highly developed teratoma is a diagnostic dilemma as it resembles fetus in fetu. The absence of a spinal axis differentiates this entity from the fetus in fetu.