How to Diagnose Epidermal Cyst

An epidermal cyst is an inclusion of epidermal cells in the dermis. The more general term of epidermoid cyst is preferred because some of these cysts arise from hair follicles. These cysts do not originate from the sebaceous glands and should not be referred to as sebaceous cysts. Epidermal cysts become cancerous on rare occasions. The following steps will show how to diagnose an epidermal cyst.

Instructions

Difficulty: Challenging

1. Use a sonogram to identify epidermoid cysts. The features are well characterized and intact cysts usually appear as spherical or ovoid masses that do not return echoes well and lack color Doppler signals. Ruptured cysts tend to have irregular contours and may show color Doppler signals.
2. View the suspected epidermoid cyst with Magnetic Resonance Imaging (MRI.) The margins are well defined and the cyst is isodense to slightly hyperdense when observed on T1-weighted images. Epidermoid cysts should show as hyperdense on T2-weighted images.
3. Take radiographs or Computed Tomography (CT) scans of epidermoid cysts with intraosseous extensions. These may occur on the ends of fingers and toes or intracranially. These may show well-defined lesions surrounded by a thin rim of bone.
4. Examine a biopsy microscopically. A sample may be taken with fine needle aspiration and stained with Wright-Giemsa. Epidermoid cysts should contain a wavy keratin material.
5. Determine the histological characteristics of an epidermoid cyst. They are usually lined with a stratified scaly epithelium with a granular layer containing keratin.