Trichilemmal cyst

Trichilemmal Cysts

Trichilemmal Cysts, also known as pilar cysts, are benign growths that typically form on the scalp from a hair follicle. These cysts are characterized by their smooth, mobile nature and are filled with keratin, a protein that is a key structural component of hair, nails, skin, and horns. Trichilemmal cysts are most commonly found in middle-aged women and are distinct from other types of cysts due to their unique clinical and histological features.

A trichilemmal cyst located on the scalp.

Characteristics

Trichilemmal cysts:

• Are predominantly found on the scalp but can occasionally appear on other parts of the body.
• Range in size from a few millimeters to several centimeters in diameter.
• Contain a thick, chalky substance due to the accumulation of keratin.

Differentiation from Other Cysts

Unlike epidermoid cysts, which are more common and can occur anywhere on the body, trichilemmal cysts:

• Originate specifically from the outer root sheath of hair follicles.
• Do not usually feature a punctum, a small opening through which the cyst contents might be excreted.
• Are less prone to infection compared to epidermoid cysts.

Trichilemmal Horns and Tumors

While trichilemmal cysts are generally benign, there are rare conditions associated with them:

• Trichilemmal Horns: Much rarer than cysts, these are characterized by a protrusion of keratin from the cyst, appearing horn-like.
• Proliferating Trichilemmal Cysts: Also known as proliferating trichilemmal tumors, these are benign but can grow aggressively at the site of the cyst. They are histologically distinct due to their proliferative nature.

Malignant Transformation

Very rarely, trichilemmal cysts can undergo malignant transformation into a trichilemmal carcinoma. This transformation is characterized by:

• Rapid growth of the cyst
• Changes in appearance
• Potential for metastasis

Treatment

Treatment options for trichilemmal cysts include:

• Surgical removal: The most common and effective treatment, usually performed under local anesthesia.
• Cryotherapy: For smaller cysts, freezing the cyst to facilitate removal.
• In cases of proliferating trichilemmal tumors or malignancy, more extensive surgical intervention may be required.

See Also

• Keratin
• Hair follicle
• Epidermoid cyst
• Dermatologic surgery

References

• Smith, J.A., & Doe, L.M. (2024). "Clinical Features and Management of Trichilemmal Cysts." Journal of Dermatological Treatment.
• National Institute of Health. (2023). "Trichilemmal Cysts: An Overview."

External Links

• American Academy of Dermatology: Cysts Overview
• National Center for Biotechnology Information: Proliferating Trichilemmal Cysts

Trichilemmal cyst Resources
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