Presentation
Bumping into things at work (which is a problem as he sells expensive knick-knacks)
Patient Data
A cystic suprasellar mass extends into the left ambient cistern and middle cranial fossa. It has near CSF intensity on T2 but is hyperintense on T1 and does not attenuate on FLAIR. No diffusion restriction or convincing solid enhancing or fatty component. No diffusion restriction (which excludes an epidermoid cyst).
The differential diagnosis includes adamantinomatous craniopharyngioma, neuroenteric cyst, teratoma or complicated arachnoid cyst.
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.
Case Discussion
In most cases of suprasellar teratomas a more convincing fatty and/or solid component can be identified preoperatively allowing a more certain diagnosis to be made on the basis of imaging alone.