Pilar sheath acanthoma

A rare benign skin tumor

Pilar Sheath Acanthoma

Pilar sheath acanthoma on the skin

A pilar sheath acanthoma is a rare, benign skin tumor that typically presents as a small, solitary, flesh-colored nodule. It is most commonly found on the face, particularly around the upper lip and nose. This tumor is considered a type of follicular tumor, originating from the hair follicle sheath.

Clinical Presentation

Pilar sheath acanthomas are usually asymptomatic and are often discovered incidentally during a routine skin examination. They appear as small, dome-shaped papules or nodules, typically measuring less than 1 cm in diameter. The surface of the lesion is smooth, and the color can range from flesh-toned to slightly erythematous.

Histopathology

Histological section of a pilar sheath acanthoma

Histologically, pilar sheath acanthomas are characterized by a well-circumscribed proliferation of basaloid cells. These cells form a cystic structure with a central keratin-filled cavity. The tumor is composed of lobules of squamous epithelium with peripheral palisading of the basal cell layer. The central cavity is lined by keratinizing squamous epithelium, resembling the outer root sheath of a hair follicle.

Differential Diagnosis

The differential diagnosis for pilar sheath acanthoma includes other benign follicular tumors such as trichofolliculoma, trichoepithelioma, and sebaceous hyperplasia. It is important to distinguish pilar sheath acanthoma from malignant lesions such as basal cell carcinoma and squamous cell carcinoma.

Treatment

Treatment is generally not necessary for pilar sheath acanthoma due to its benign nature. However, if the lesion is cosmetically concerning or if there is uncertainty in the diagnosis, surgical excision may be performed. Complete excision is usually curative, and recurrence is rare.

Prognosis

The prognosis for individuals with pilar sheath acanthoma is excellent. These tumors do not have malignant potential and do not metastasize. Once excised, they typically do not recur.

Related pages

• Trichofolliculoma
• Trichoepithelioma
• Basal cell carcinoma
• Squamous cell carcinoma