The patient went on to have surgery.

Histology

MICROSCOPIC DESCRIPTION:

1. Sections show cyst wall comprising stratified squamous epithelium lacking a granular layer surrounded by fibrous stroma with scattered chronic inflammatory cell infiltrate. Attached adnexal structures are not seen. There is no evidence of malignancy.

2. Sections show sheets of compact acellular keratin. There is no evidence of malignancy.

FINAL DIAGNOSIS:

1. cyst wall: benign squamous cyst, consistent with an epidermoid cyst.
2. cyst content: Acellular keratin debris.

Angular dermoids are the most common cystic lesions to be found in this location, however, in the absence of a fatty (sebum) component or other secondary skin appendages (e.g. hair) it is difficult to confidently make the diagnosis preoperatively. The other possibility is that of an intradiploic epidermoid cyst.