Ovarian fetiform teratoma (homunculus) in a 9-year-old girl.

An infarcted ovarian mass, removed from a 9-year-old girl, was composed of a thin-walled cyst containing a fetiform structure. At its cranial pole was a ruptured cyst lined by skin and a diaphanous fibrous membrane associated with long, darkly pigmented hair. The remainder of the fetiform structure was covered by skin bearing fine lanugo hair. Rudimentary upper limb buds were present. At the caudal pole were two extremities that included feet, toes, and nails. Radiographic studies demonstrated portions of skull, vertebral, and limb bones. Microscopical examination revealed primitive brain tissue at the base of the cephalic cavity and a spinal cord along the entire length of the trunk with ganglia and peripheral nerves extending outward from it. Notochordal tissue was associated with one vertebral body. A mucus-filled endodermal tube containing glandular outgrowths also ran the length of the trunk. This patient is one of the youngest reported with an ovarian homunculus or fetiform teratoma. This specimen is among the very few recorded cases in the literature and reflects the highest degree of organized development exhibited by a single germ cell undergoing neoplasia.