Dermoid cyst pathology

Dermoid cysts are derived from the ectoderm and involve embryologic closure lines.

Histology of dermoid cyst

Sections show a subcutaneous cyst which is often received “shelled out” (figure 1).

The lining is typically a keratinizing squamous epithelium (figures 2, 3). The hallmark of these cysts is the presence of pilosebaceous structures in the cyst wall (figures 2, 3). Hair shafts are often found within the cyst (figure 3, arrow).

Less common findings include a columnar or mucous secreting epithelium, smooth muscle in the cyst wall, and surrounding eccrine glands.

Figure 1

Figure 2

Figure 3

Special studies for dermoid cyst

None are needed.

Differential diagnosis of dermoid cyst pathology

Steatocystoma – Steatocystoma shows sebaceous glands connecting to the cyst lining but the pilar structures are not seen. The lining lacks a granular layer and has a characteristic corrugated keratin layer.