Use of immunohistochemical stains to assess the variations in color of fat of the upper eyelid

Although there are many variations on the technique, most practitioners agree that removal of periorbital eyelid fat is an integral part of the blepharoplasty operation. The retrieval and excision of the medial fat of the upper eyelid is a step that, when overlooked, leaves the patient with an unsatisfactory appearance of puffiness in this area. The medial fat is characteristically white; the other fat compartments are yellow. The authors attempt to understand why these two juxtaposed fat pockets are of distinct different colors. Four consecutive patients underwent traditional upper blepharoplasty surgery. From each patient two separate fat specimens were identified as upper lateral and upper medial. These fat specimens were processed with hematoxylin and eosin and various immunohistochemical stains. A board-certified pathologist, who was blinded as to the anatomic site of the fat, evaluated them. The medial fat showed much larger fat lobules than the upper lateral fat. Contrasting this, the lateral fat had many more endothelial-lined blood vessels and much thicker fibrous septa than its medial neighbor. These findings were supported immunohistochemically by using CD34 (endothelial antibody) and factor XIIIa (dermal dendritic cell/ normal fibroblast antibody). The use of other immunostains using various antibodies did not distinguish any distinct histomorphology among the specimens. Although for the operating surgeon it is important to recognize the white color of the medial fat to aid in identification during surgery, one can only speculate as to what contributes to this difference in blood vessels and supporting fibrous septa. Most likely this is the result of anatomic, embryologic, and vascular bed differences.