title: Sacral parasite conjoined twin.
abstract: BACKGROUND
  A variant of conjoined twins is one in which one twin is incomplete.
  
  
  METHODS
  A female infant was born vaginally at 40 weeks' gestation to a healthy primipara. No important abnormalities were noted during prenatal examinations. The infant was fully developed in all external aspects except for a parasitic body conjoined with her sacrococcygeal region. Separated by operation 2 weeks after birth, the parasite contained lower limbs, adipose tissue, muscles, and a bowel sac. Over 4 years of observation, no abnormalities have been found since the operation.
  
  
  CONCLUSIONS
  Obstetricians should be aware of the existence of a parasite twin during prenatal examinations and of the importance of the differential diagnosis of parasite and teratoma, a neoplasm with malignant potential.
authors.affiliation: Department of Obstetrics and Gynecology, Taipei Medical University-Municipal Wan Fan Hospital, Taipei, Taiwan.
authors.forename: S Y
authors.initials: SY
authors.lastname: Chou
authors.forename: S J
authors.initials: SJ
authors.lastname: Liang
authors.forename: C F
authors.initials: CF
authors.lastname: Wu
authors.forename: C S
authors.initials: CS
authors.lastname: Hsu
mesh_terms: D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D012445:Sacrococcygeal Region; D013724:Teratoma / Q000175:diagnosis; D014428:Twins, Conjoined / Q000601:surgery