31 year old woman with ovarian tumor, which was excised. (No clinical data or macroscopic view of the tumor is avaliable).  
 
HISTOLOGY: Ovary with a cyst lined with keratinizing squamous epithelium with pancreas and salivary gland serosal-mucinous acini, ductal structures, ganglia and cysts with cuboidal, ciliated epithelial lining in subepidermal stroma (derma). There is abundant mature brain tissue (neuropil) with cyst, lined with cuboidal epithelium (ependima).  
There is a tumor in neuropil, composed of interflowing nests, composed of medium sized monotonous cells with faintly polymorphous nuclei with single nucleoli and vacuolized light eosinophilic cytoplasm. There are few nests of pigmented cells – retina tissue, in the tumor and next to it. There are intraductal eosinophilic structures (plexus chorioideus), ganglia.  
 
IH: PanCK(-); CD56/Synaptophysin/NSE/NFP+; Chrogranin A(-/+); GFAP/CD57(-); S100+.  
 
The diagnosis formulated as:  
Mature (monodermal) ovarian teratoma ("dermoid cyst") with somatic CNS tumor: central neurocytoma (extraventricular) (II° PSO).  
 
Would be grateful for other variants, suggestions and comments.