Dermal Cysts: Definition, Types, and Management

Types and Characteristics

Epidermoid cysts contain cheesy keratinous material and normal skin flora even when uninflamed, according to the Clinical Infectious Diseases guidelines 1
Dermoid cysts are congenital choristomas that may contain more complex structures like hair, teeth, and cartilage due to their developmental origin, as noted by Praxis Medical Insights 2

Most dermal cysts present as asymptomatic nodules unless complicated by rupture or infection, as reported by Clinical Infectious Diseases 1
When inflamed, epidermoid cysts can present as painful, tender swellings that may mimic abscesses, according to Clinical Infectious Diseases 3
Dermoid cysts show hyperechoic components with acoustic shadowing, hyperechoic lines and dots, and sometimes fluid-fluid levels on ultrasound, as described by Radiology and Praxis Medical Insights 4, 2

Inflammation and purulence in epidermoid cysts typically occur as a reaction to rupture of the cyst wall and extrusion of contents into the dermis, rather than as a primary infectious process, as explained by Clinical Infectious Diseases 1, 3

For inflamed epidermoid cysts, effective treatment involves incision and thorough evacuation of the contents, probing the cavity to break up loculations, and covering the surgical site with a dry dressing, as recommended by Clinical Infectious Diseases 1, 3
Systemic antibiotics are rarely necessary for inflamed cysts unless there are complicating factors such as multiple lesions, cutaneous gangrene, severely impaired host defenses, extensive surrounding cellulitis, or severe systemic manifestations of infection, according to Clinical Infectious Diseases 1, 3

Dermoid cysts in specific locations require specialized management approaches and monitoring, especially in postmenopausal patients due to increased risk of malignant transformation, as noted by Radiology and Praxis Medical Insights 4, 2

Potential complications of dermal cysts include rupture leading to inflammation, as reported by Clinical Infectious Diseases 1
Secondary infection is also a potential complication of dermal cysts, according to Clinical Infectious Diseases 3

The American College of Radiology recommends ultrasound as the preferred initial imaging modality for superficial finger masses when the diagnosis is uncertain, demonstrating a sensitivity of 94.1 % and specificity of 99.7 % for superficial soft‑tissue lesions. 5

The American College of Radiology recommends obtaining plain radiographs of the affected finger to assess for distal interphalangeal (DIP) joint osteoarthritis and osteophytes, possible intra‑osseous extension of cysts, and any underlying bone pathology. 5