Palisaded encapsulated neuroma (PEN) is a rare, benign

cutaneous condition A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of this sys ...

characterized by small, firm, non-pigmented

nodules Nodule may refer to: *Nodule (geology), a small rock or mineral cluster *Manganese nodule, a metallic concretion found on the seafloor *Nodule (medicine), a small aggregation of cells *Root nodule Root nodules are found on the roots of plants, p ...

papules A papule is a small, well-defined bump in the skin. It may have a rounded, pointed or flat top, and may have a dip. It can appear with a stalk, be thread-like or look warty. It can be soft or firm and its surface may be rough or smooth. Some ...

. They typically occur as a solitary (single)

lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by injury or diseases. The term ''Lesion'' is derived from the Latin meaning "injury". Lesions may occur in both plants and animals. Types There is no de ...

near the

mucocutaneous junction A mucocutaneous junction, or mucocutaneous boundary, is a region of the body in which mucosa transitions to skin. Mucocutaneous zones occur in animals, at the body orifices. In humans, mucocutaneous junctions are found at the lips, nostrils, conjun ...

of the skin of the face, although they can occur elsewhere on the body.

Symptoms

PEN tumours are always painless, solid masses felt on the skin that, due to their slow-growing nature, typically take many years to grow to a size where they are noticeable. There are never any symptoms associated with systemic disease.

Diagnosis

As mentioned previously, PEN is a benign, firm, flesh-coloured lesion that typically occurs in

dermis The dermis or corium is a layer of skin between the epidermis (skin), epidermis (with which it makes up the cutis (anatomy), cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from s ...

of the skin of the face. The lesions are typically between 2–6mm and are slow-growing. On the face, the lesions can be found on the eyelid, nose and in the

oral mucosa The oral mucosa is the mucous membrane lining the inside of the mouth. It comprises stratified squamous epithelium, termed "oral epithelium", and an underlying connective tissue termed '' lamina propria''. The oral cavity has sometimes been des ...

, however, the lesions can also occur on the shoulder, arm, hand, foot and the glans of the penis. PEN is diagnosed by clinical recognition of the lesion and on subsequent histologic examination. Typically, the lesions are suspected to be

schwannomas A schwannoma (or neurilemmoma) is a usually benign nerve sheath tumor composed of Schwann cells, which normally produce the insulating myelin sheath covering peripheral nerves. Schwannomas are homogeneous tumors, consisting only of Schwann cells ...

neurofibromas A neurofibroma is a benign nerve-sheath tumor in the peripheral nervous system. In 90% of cases, they are found as stand-alone tumors (solitary neurofibroma, solitary nerve sheath tumor or sporadic neurofibroma), while the remainder are found in ...

clinically with PEN being an incidental finding on histology. PEN is typically diagnosed in patients between the ages of 40 and 60 years and occurs more frequently in females than males. The diagnosis of PEN may be difficult, even with confirmatory histology, due to its histological similarities with schwannomas and neurofibromas. It is imperative that the correct diagnosis is made the misdiagnosis of a neurofibroma may lead to unnecessary further investigation into associated systemic syndromes such as

neurofibromatosis type 1 Neurofibromatosis (NF) refers to a group of three distinct genetic conditions in which tumors grow in the nervous system. The tumors are non-cancerous (benign) and often involve the skin or surrounding bone. Although symptoms are often mild, e ...

or multiple endocrine neoplasia syndrome. The differential diagnosis for PEN includes a

neurofibroma A neurofibroma is a benign nerve-sheath tumor in the peripheral nervous system. In 90% of cases, they are found as stand-alone tumors (solitary neurofibroma, solitary nerve sheath tumor or sporadic neurofibroma), while the remainder are found in ...

basal cell carcinoma Basal-cell carcinoma (BCC), also known as basal-cell cancer, basalioma, or rodent ulcer, is the most common type of skin cancer. It often appears as a painless, raised area of skin, which may be shiny with Telangiectasia, small blood vessels ru ...

melanocytic nevus A melanocytic nevus (also known as nevocytic nevus, nevus-cell nevus, and commonly as a mole) is usually a Malignancy, noncancerous condition of pigment-producing Human skin, skin cells. It is a type of melanocytic tumor that contains nevus cell ...

epidermoid cyst An epidermoid cyst or epidermal inclusion cyst is a benign cyst usually found on the skin. The cyst develops out of ectodermal tissue. Histologically, it is made of a thin layer of squamous epithelium. Signs and symptoms The epidermoid cyst may ...

and a

skin appendage Skin appendages (or adnexa of skin) are anatomical skin-associated structures that serve a particular function including sensation, contractility, lubrication and heat loss in animals. In humans, some of the more common skin appendages are hairs ( ...

Treatment

The only definitive treatment of PEN is

surgical excision Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery ...

. Excision is curative and rarely recur.

Gallery

File:Palisaded and Encapsulated Neuroma (978575618).jpg File:Palisaded and Encapsulated Neuroma (3952635881).jpg File:Palisaded and Encapsulated Neuroma, S-100 Immunostain (3953412396).jpg File:Skin Tumors-PA291040.jpg File:Skin Tumors-PA291039.jpg

References

Dermal and subcutaneous growths

External links