Angular epidermoid cyst

Case contributed by Assoc Prof Frank Gaillard

Presentation

Proptosis.

Patient Data

Age: 35 Years
CT

A bony defect in the superolateral aspect of the left orbit and extending into the anterior cranial fossa is filled with a lobulated low density lesion, without calcification, fat or enhancement. Mild proptosis noted. 

MRI

A well circumscribed lobulated mass arising from the upper outer quadrant of the left of orbit with bony remodeling and extension into the anterior cranial fossa is present. It is located posterior to the orbital segment and is mostly low T1 and high T2 is signal without enhancement. Peripheral areas of intrinsic high T1 do not attenuate on fat saturated sequences. No particularly high signal on DWI is noted. 

Case Discussion

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.

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