Nevus Sebaceous - Symptoms, Diagnosis, and Treatment

Introduction

Nevus sebaceous is a rare type of birthmark present on the scalp, face, neck, and forehead. It consists of an overgrown epidermis (upper layer of the skin), sebaceous glands (oil-producing glands in the skin), hair follicles, and connective tissue.

What Is Nevus Sebaceous?

Nevus sebaceous is a type of birthmark that may be present on the neck, forehead, or scalp. It can occur anywhere on the head, but the most common site remains the scalp. It can be classified as a hair follicle tumor and may be associated with other conditions. It is usually benign. In infants or young children, sebaceous nevus usually looks like a solitary, smooth, yellow-orange hairless patch, often oval or linear in shape. It becomes more prominent during adolescence and appears scaly, watery, and bumpy.

What Are the Symptoms of Nevus Sebaceous?

Nevus sebaceous is present differently in young children and infants and in a different way in adults.

• In young children and infants: It is a yellow-orange patch of smooth and hairless skin. It is well-circumscribed, has well-defined borders, and is likely to appear oval or linear. Usually, only one layer of the skin is affected, which looks like a plaque. Due to hormonal fluctuations, the lesion may change during puberty. In some cases, when the lesion is diagnosed, it may start changing its appearance.

• In adolescence: As a person attains maturity, the lesion may change its appearance as the epidermis starts getting thickened. It becomes either more prominent or appears bumpy or scaly. The size of the nevi grows as the person grows. Usually, sebaceous nevi are painless and do not itch unless secondary complications arise, like sores. It only has aesthetic concerns. One lesion is generally present, mainly on the scalp, and in rare cases, multiple numbers are seen. Sometimes, nevi sebaceous is accompanied by nevi sebaceous syndrome. This is a low condition that causes -

  • Seizures.

  • Hemimegalencephaly (enlargement of one side of the brain).

What Are the Causes of Nevus Sebaceous?

Nevus sebaceous is a congenital malformation. It comes from a defect in the layer called the ectoderm (outer layer of the embryo) before birth. The ectoderm is responsible for the formation of both neural tissue and the epidermis. In the case of nevi sebaceous, the epidermis becomes thicker over time. Family history also plays an important role in causing this disease. A person having nevi sebaceous has the most chance of passing it to the children. Another reason could be a mutation in the PTCH gene. Mutation in the PTCH-1 gene is a predisposing factor to cause a skin cancer called basal cell carcinoma (a type of skin cancer that begins in the basal cells that line the epidermis). For this reason, regular examinations of the skin are suggested by dermatologists to detect such diseases. It affects both men and women equally.

How Is Nevus Sebaceous Diagnosed?

Nevus sebaceous can be diagnosed in many ways. All nevi sebaceous are present by birth; they can be diagnosed in early infancy or childhood. Parents or doctors usually notice them.

The doctors diagnose it by taking a proper medical history from the parents and by performing a thorough physical examination. Some other ways to diagnose it include:

• Skin Biopsy: Skin biopsy is a technique in which a part of the tissue is excavated from the skin under local anesthesia and studied under a microscope. It is used to check whether a condition is benign or malignant. During childhood, a biopsy of the nevus sebaceous is a hairless condition and is seen as an immature sebaceous gland and hair follicles and thickening of the epidermis. In adults, the lesion contains mature sebaceous glands and hair follicles and thickening of the epidermis largely. Most of the nevus sebaceous remains unaltered for lifelong. In some cases, it may convert into a tumor. These tumors are frequently benign, but one should contact the doctor immediately if any changes are noticed.

• CT (Computed Tomography) scans: CT-scans help the doctor to check for atypical characteristics and find out the best method for surgical procedures.

• Ultrasounds: Ultrasounds are used to locate the cyst and recognize its contents.

How Is Nevus Sebaceous Treated?

Nevus sebaceous is not a serious medical condition usually. It does not require much treatment until it remains unchanged and is stable. If any bumps or sores are seen, they should be treated. It is necessary because skin cancers like basal and squamous cell carcinomas are caused in most people suffering from nevus sebaceous. Some people choose to remove it permanently due to aesthetic conditions and complications. In some cases, they can be removed by surgical excision; scarring cannot be avoided and will be permanent after removal. The doctor may use any of the following methods to remove the cyst:

• Conventional Wide Excision: This removes a cyst completely, but it can leave a long scar.

• Minimal Excision: A method that causes minimal scarring but has a risk that the cyst will appear again.

• Laser With Punch Biopsy Excision: This technique uses a laser to make a small hole to drain the cyst of its contents (the outer walls of the cyst are removed about a month later). It is done in cases of aesthetic concern or to prevent malignant growth; it is the best option. It leaves a smaller scar than the one caused by surgical excision.

Conclusion

This article describes a condition called nevus sebaceous, its causes, signs and symptoms, diagnosis, and treatment. Nevus sebaceous is a condition in which a birthmark is present on the scalp. It can also be present on other sites, such as the face, neck, forehead, etc. It is caused due to congenital malformations and genetic mutations in the PTCH genes. Since most of the nevus sebaceous are present by birth, they can be diagnosed by doctors or parents. This condition does not require much treatment as it is benign and does not cause much pain or itching. But in some cases, people remove it by surgical excision or laser therapy for aesthetic reasons. In most cases, they remain unchanged for their entire life. While in some, they may turn into skin cancers like basal cell carcinoma. Therefore, proper monitoring from time to time and treatment is required.