Under local anesthesia, an incisional biopsy was performed and a small specimen was submitted for histologic evaluation. Following an initial diagnosis, the lesion was removed in its entirety under general anesthesia at Overlake Hospital Medical Center.

Incisional Biopsy

Histological examination revealed multiple pieces of soft tissue composed of a cystic structure and keratin fibers (Figures 2-4). The cystic structure is lined by uniformly thin and keratinized epithelium and supported by a fibrous connective tissue wall (Figures 2 & 3). The lining epithelium is covered by a thin layer of parakeratin and orthokeratin (Figures 2 & 3). The lumen of the cyst contains keratin fibers (Figure 4). The connective tissue wall comprises the bulk of the specimen. It is myxoid in most parts and focally infiltrated by a small cluster of lymphocytes with occasional plasma cells.

Figure 2 Low power (x100) H & E stained histology shows a cystic structure lined by uniformly thin, keratinized and slightly corrugated stratified squamous epithelium. The latter is supported by loose and myxoid fibrous connective tissue wall.

Figure 3 Higher power (200) H & E stain histology shows the thin and keratinized stratified squamous epithelium to be focally artifactually split from the connective tissue. It also shows focal basal cells arranged in a palisaded manner.

Figure 4 Higher power (200) H & E stain histology shows keratin fibers in the lumen of the cyst.