Epidermal Inclusion Cyst
Epidermoid Cyst of Bone

General Considerations

• Associated with trauma, especially penetrating trauma
• Usually in bones that are superficially located such as fingers, foot and calvarium
• Implantation of epithelium that form cysts leading to bone erosion
• Subungual crush-type injuries have been associated with inclusion cysts as has prior surgery

Clinical Findings

• May develop with in weeks or years of fingertip injury
• Pain at site of lesion
• Mass

Imaging Findings

• Frequently seen in terminal phalanx
• Solitary, lytic lesion
• May be expansile
• May have a thin sclerotic border

Differential Diagnosis

• Enchondroma
• Metastases (rare)
• Glomus tumor

Treatment

• Surgical curettage

Complications

• May recur if incompletely curetted

Prognosis

• Excellent 

Epidermal Inclusion Cyst. White arrows pint to an expansile lytic lesion in the terminal phalanx
of the index finger in a characteristic location for an epidermal inclusion cyst of the hand.
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