Epidermal Cyst of the Plantar Foot: A Case Study

Abstract

Epidermal inclusion cysts (also commonly referred to as epidermal cysts, epidermoid cysts and infundibular cysts) are benign cysts in the epidermal region of the skin. Comprising about 85-90% of all excised subcutaneous cysts, they are relatively common. [2-4]. The cyst is most often found in the hair bearing surfaces of the body due to a displacement and proliferation of the epidermal cells within the dermis, or from inflammation of the pilosebaceous glands. The most common locations include the head, neck, trunk, extremities, with less than 10% presenting in the lower extremity [2,5]. However, epidermoid cysts may occasionally appear on non-hair-bearing Surfaces of the body. These cysts are thought to develop due to a history of trauma or surgery that implanted the epidermal cells in the area. Specifically, the cysts develop from epidermal fragments into a heterotropic location. The cyst enlarges through keratinous debris and epithelial accumulation, resulting in a subcutaneous mass [5]. In the foot, epidermoid cysts occurred most commonly in the 1st toe, followed by the ankle, 2nd toe, 3rd toe, 4th toe, 5th toe, and heel. The average size of the cyst in the foot is 1.6 x 1.5 x 0.8cm. Treatment of epidermoid cysts includes excision but recurrence rates appear to be high at 18.9 %. [3,4]. Epidermal inclusion cysts present clinically as well-encapsulated, freely movable, elevated subcutaneous masses. The masses contain a yellow and white substance in the center [5]. Since 2000, there have only been 2 reported cases of epidermoid cysts on the plantar foot [6,7]. We will be reporting a 3rd case within a period of 17 years.