Palisaded encapsulated neuroma

Palisaded Encapsulated Neuroma (PEN) is a benign cutaneous condition characterized by a solitary, firm, skin-colored or pink nodule, typically occurring on the face, particularly the nose. It is a non-cancerous growth that arises from the peripheral nerves and is composed of Schwann cells, fibroblasts, and perineural cells. Despite its benign nature, it can sometimes be mistaken for malignant tumors, such as basal cell carcinoma or malignant melanoma, due to its appearance.

Etiology and Pathogenesis

The exact cause of Palisaded Encapsulated Neuroma is unknown. It is considered to be a reactive process rather than a true neoplasm. Trauma or a history of minor injuries to the affected area has been suggested as a possible trigger for the development of PEN. Histologically, it is characterized by a well-circumscribed nodule composed of spindle-shaped Schwann cells arranged in a palisaded pattern. These cells are surrounded by a fibrous capsule, which is where the term "encapsulated" in its name comes from.

Clinical Features

Palisaded Encapsulated Neuroma typically presents as a solitary, asymptomatic, skin-colored or pink nodule. The size of the lesion usually ranges from 2 to 6 mm in diameter. It is most commonly located on the face, especially on the nose, but can also appear on other parts of the body such as the neck, trunk, and extremities. PEN does not usually cause any symptoms, but some patients may experience tenderness upon palpation.

Diagnosis

The diagnosis of Palisaded Encapsulated Neuroma is primarily based on histopathological examination. Dermoscopy can be a useful non-invasive tool in the initial assessment, but a definitive diagnosis requires a biopsy of the lesion. Histologically, PEN is distinguished by its well-defined capsule and the presence of Schwann cells arranged in a palisaded pattern around axons, without atypia or mitotic figures.

Differential Diagnosis

The differential diagnosis for Palisaded Encapsulated Neuroma includes several other cutaneous lesions such as neurofibroma, schwannoma, and various skin cancers. Clinical and histopathological evaluation is essential to differentiate PEN from these conditions.

Treatment

Since Palisaded Encapsulated Neuroma is a benign lesion, treatment is not always necessary unless for cosmetic reasons or if the lesion is symptomatic. Surgical excision is the most common treatment method and is usually curative. Recurrence after complete excision is rare.

Prognosis

The prognosis for Palisaded Encapsulated Neuroma is excellent, as it is a benign lesion with no malignant potential. Surgical removal is curative in most cases, and recurrence is uncommon.

Epidemiology

Palisaded Encapsulated Neuroma can occur at any age but is most commonly diagnosed in adults. There is no known gender predilection. The prevalence of PEN is not well documented, as many cases may go unrecognized or misdiagnosed.

Conclusion

Palisaded Encapsulated Neuroma is a benign peripheral nerve sheath tumor that typically presents as a solitary, asymptomatic nodule on the face. Despite its benign nature, accurate diagnosis through histopathological examination is crucial to differentiate it from other cutaneous lesions, including malignant tumors. Surgical excision is the treatment of choice and is usually curative.

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