Reported here is a case of Müllerian adenosarcoma of the
ovary which contained a primitive neuroectodermal tissue
component within the stroma. The adenosarcoma coexisted
with clear cell adenocarcinoma in an endometriotic cyst.
The patient was a 33-year-old woman with a large unilocular
endometriotic cyst of the right ovary. On the internal wall of
the cyst, both a plaque-like protrusion with a papillary
surface and a dome-like mural nodule were noted. The
former exhibited features of Müllerian adenosarcoma, and
the latter showed those of clear cell adenocarcinoma. In the
deeper portion of adenosarcoma, teratoma-like tissue which
contained various tissue components including primitive
neuroectodermal tissue was found. The presence of primitive
neuroectodermal tissue in the stroma of adenosarcoma
suggested the diagnosis of ‘adenosarcoma with neuroectodermal
differentiation’ (‘teratoid adenosarcoma’), although
the possibility of the incidental occurrence of an immature
teratoma could not be completely excluded.