The patient went on to have surgery
Histology
Sections of the parts labeled as cyst wall reveal that the fibrovascular wall of the cyst is lined by variable adult-type mature epithelium ranging from stratified squamous epithelium to simple cuboidal to pseudostratified epithelium. Nests of squamous epithelial cells are seen within the wall (probably tangentially cut).
Occasional duct-like structures are seen in the connective tissue and within adipose tissue, there are mucin-secreting glandular structures with myoepithelial cells, consistent with salivary glands.
Focally there is an infiltrate of hemosiderin-laden and lipid-laden HAM56-positive macrophages in the connective tissue admixed with lymphocytic infiltrates. The epithelial lining is strongly positive for keratin immunostain. There are few scattered mucin positive epithelial cells by mucicarmine stain that are also evident by PAS (with diastase) stain.
FINAL DIAGNOSIS: Given the fact that the cyst wall has endodermal cuboidal/pseudostratified epithelium and mucin-secreting glands) and mesodermal (fibrovascular and adipose tissue) components, this is best regarded as a di-dermal mature teratoma. The stratified squamous epithelium, which is continuous with the cuboidal /pseudostratified epithelium, probably represents squamous metaplasia rather than an ectodermal component per se.