Trichilemmoma

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
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Trichilemmoma
Trichilemmoma
Synonyms	N/A
Pronounce	N/A
Specialty	Dermatology
Symptoms	Skin lesion
Complications	N/A
Onset	Middle-aged adults
Duration	Chronic
Types	N/A
Causes	Genetic mutation
Risks	Cowden syndrome
Diagnosis	Biopsy
Differential diagnosis	Basal cell carcinoma, Seborrheic keratosis
Prevention	N/A
Treatment	Surgical excision
Medication	N/A
Prognosis	Excellent
Frequency	Rare
Deaths	N/A

A benign cutaneous neoplasm derived from the outer root sheath of hair follicles

Trichilemmoma is a benign cutaneous neoplasm that originates from the outer root sheath of hair follicles. It is characterized by its distinctive histological features and is often associated with certain genetic conditions. Trichilemmomas are typically found on the face, particularly around the nose and upper lip, and are more common in adults.

Clinical Presentation

Trichilemmomas usually present as small, solitary, flesh-colored papules. They are often asymptomatic and are discovered incidentally during routine skin examinations. The lesions are typically smooth and dome-shaped, measuring a few millimeters in diameter.

Histopathology

Histologically, trichilemmomas are characterized by lobular proliferation of clear cells that resemble the outer root sheath of the hair follicle. The clear cells have abundant glycogen-rich cytoplasm, and the lesions often exhibit a well-defined border. The presence of palisading of the outermost layer of cells is a common feature.

Histological image of trichilemmoma

Pathogenesis

The pathogenesis of trichilemmoma involves the proliferation of cells from the outer root sheath of the hair follicle. This proliferation is benign and does not typically lead to malignant transformation. However, multiple trichilemmomas can be a feature of certain genetic syndromes, such as Cowden syndrome, which is associated with mutations in the PTEN gene.

Diagnosis

The diagnosis of trichilemmoma is primarily based on histological examination. A biopsy of the lesion is performed, and the characteristic histopathological features confirm the diagnosis. Dermoscopy may aid in the clinical diagnosis by revealing specific patterns associated with trichilemmomas.

Treatment

Treatment is generally not necessary for solitary trichilemmomas unless they are symptomatic or cosmetically concerning to the patient. In such cases, surgical excision is the treatment of choice. For patients with multiple lesions associated with genetic syndromes, regular monitoring and management of associated conditions are recommended.

Prognosis

The prognosis for patients with trichilemmoma is excellent, as these lesions are benign and do not metastasize. However, patients with multiple trichilemmomas should be evaluated for underlying genetic conditions that may require further management.

See also

• Cowden syndrome
• PTEN gene
• Hair follicle
• Cutaneous neoplasm