What is Nevus Sebaceus?
The Nevus sebaceus of Jadassohn, also called an organoid nevus, is a birthmark that was first described in 1895 by a skin doctor named Josef Jadassohn. These birthmarks are abnormal growths of hair and oil gland units in the skin. They usually form on the scalp but can also appear on the forehead, face, or neck. These skin growths tend to get bigger around puberty due to changes in hormones in the body. In adulthood, the nevus sebaceus can develop small benign (non-cancerous) skin tumors within them, most commonly a type called trichoblastoma. There is no agreed upon single method of treatment for these skin abnormalities, with options ranging from monitoring the growth to removing it in childhood.
Nevus sebaceus syndrome, also known as Schimmelpenning Feuerstein Mims Syndrome, includes having a large or widespread nevus sebaceus and abnormalities in the brain, bones, or eyes. There’s also a rare subcategory of this syndrome called phakomatosis pigmentokeratotica (PPK). In PPK, a person has both nevus sebaceus and another kind of birthmark called a speckled lentiginous nevus.
What Causes Nevus Sebaceus?
In the past, experts believed that a potentially harmful form of cancer, known as secondary carcinoma, often developed in a skin condition called nevus sebaceus. Nevus sebaceus is a benign (noncancerous) skin lesion that usually appears at birth or in early childhood. But recent research has shown that most growths that develop later in life in nevus sebaceus are actually non-cancerous.
Now, many theorize that growths, once thought to be cancerous and identified as basal cell carcinoma (a type of skin cancer), in nevus sebaceus were likely misdiagnosed. The likely culprits are benign skin tumors, specifically trichoblastomas, which can look very similar to basal cell carcinoma under a microscope. So, while it was previously thought that basal cell carcinoma was common in nevus sebaceus, the actual occurrence of this type of skin cancer in nevus sebaceus is now known to be less than 1%.
The most common type of tumor in nevus sebaceus is, indeed, trichoblastoma, then followed by syringocystadenoma papilliferum. Other common benign tumors that can develop include tricholemmoma, sebaceous adenoma, desmoplastic tricholemmoma, apocrine adenoma, and poroma. All these terms are names of different benign skin growths.
Risk Factors and Frequency for Nevus Sebaceus
Nevus sebaceus is a condition that affects about 0.3% of newborns, without any gender preference. It affects people of all races and ethnicities. Often, this condition becomes noticeable at birth as a single mark. However, sometimes it’s not recognized until after puberty when a more distinctive wart-like feature fully emerges.
Signs and Symptoms of Nevus Sebaceus
The skin lesions or marks commonly associated with Nevus Sebaceus are typically present at birth or appear shortly after. Initially, they may appear as a single smooth, yellow, clearly defined patch. This patch could be oval or linear in shape. If there are multiple patches, they often follow the Blaschko’s lines, which are invisible lines on the skin. These marks usually don’t cause any discomfort. If the mark is on the scalp, it’s often associated with partial or complete baldness in that area. The appearance of Nevus Sebaceus can change and become more noticeable during puberty due to hormonal changes, causing the patch to become rough or have a bumpy appearance, similar to the normal changes in oil glands of the skin. People or their parents may visit a skin specialist for a check-up or to potentially remove the mark due to the way it looks.
While it’s extremely rare, the doctor may also examine the patient for other physical characteristics, such as an eye coloboma (a hole in one of the structures of the eye), a clouded cornea, misalignment of the eyes (strabismus), curvature of the spine, dislocated hips, or limb deformities. If any of these are present, the patient may be referred to an eye doctor or orthopedist. In cases where these characteristics are seen, a neurologist may also need to assess the patient since there could be neurological effects, like seizures, that may not be obvious through a physical exam alone.
Testing for Nevus Sebaceus
Nevus sebaceus is usually identified through a simple visual examination by a healthcare professional, hence, additional tests are mostly not required. However, in some cases, particularly when a child has nevus sebaceus syndrome, the child may develop a large or multiple lesions related to other parts of the body like the eyes, bones, or central nervous system. If such additional physical irregularities are present, it might be necessary for the child to see a neurologist or other specialists.
Treatment Options for Nevus Sebaceus
The treatment for a skin condition called nevus sebaceus can vary. It used to be thought that people with this skin condition could be at risk of developing skin cancers, and therefore removing the nevus sebaceus through surgery was seen as a preventive measure. However, new studies suggest that the risk of skin cancer is actually quite low, whereas there’s an increased possibility of forming non-cancerous lumps on the skin.
Most of these non-cancerous lumps only start appearing in adults who are 40 years or older. Surgery can be used to remove the nevus sebaceus as early as late childhood, but only when the risk from general anesthesia (a kind of medication that puts you to sleep) is lower or the child is old enough to handle the procedure with local anesthesia (a medication that numbs a small area of your body).
When deciding if a surgery should be done, factors such as the size and location of the skin condition should be taken into account. Lower impact procedures like shave removal (removing the top part of the skin’s surface), dermabrasion (rubbing the skin with a special instrument that smoothes the top layers of skin), or laser resurfacing (using laser beams to improve the look of the skin) usually cannot successfully remove the entire skin condition.
What else can Nevus Sebaceus be?
When it comes to diagnosing a skin condition known as nevus sebaceus, what other conditions are considered often depends on how far along in its development the nevus sebaceus is. In early infancy, the doctor might consider whether the symptoms align better with other conditions like:
- Aplasia Cutis Congenita (a condition where a newborn’s skin is missing from certain areas)
- Mastocytoma (a type of skin disorder often presenting as a lump or bump)
However, as one grows older, other conditions might be considered as a potential diagnosis. These include:
- Congenital nevus (a type of birthmark)
- Epidermal nevus (noncancerous skin growth)
- Seborrheic keratosis (a common noncancerous skin growth in older adults)
- Verruca (also known as a wart)
- Juvenile xanthogranuloma (a benign skin condition in young children that leads to small, firm bumps on the skin)
What to expect with Nevus Sebaceus
In most cases, nevus sebaceus, a type of skin lesion, will have a harmless progression. However, there are rare instances where the condition can lead to secondary cancer or complications of nevus sebaceus syndrome – a condition characterized by the presence of nevus sebaceus along with other abnormalities. In such instances, the outlook can vary.
Possible Complications When Diagnosed with Nevus Sebaceus
The chances of cancer occurrence is very low, especially in children. Notwithstanding, apart from the formation of a skin cancer named basal cell carcinoma, there are other infrequent secondary cancers that may develop. These include sebaceous carcinoma (a skin cancer that begins in oil glands), squamous cell carcinoma (a skin cancer that starts in squamous cells), microcystic adnexal carcinoma (a rare form of skin cancer), and melanoma (a serious type of skin cancer).
The Rare Possibilities of Secondary Cancer:
- Basal cell carcinoma (Skin cancer)
- Sebaceous carcinoma (Skin cancer in oil glands)
- Squamous cell carcinoma (Skin cancer in squamous cells)
- Microcystic adnexal carcinoma (Rare skin cancer)
- Melanoma (Serious skin cancer)
Preventing Nevus Sebaceus
Patients should understand that nevus sebaceus is generally a harmless skin change that may appear as a wart-like patch on the scalp when it has fully grown. We wish to assure patients that the chances of this turning into cancer are extremely low, and if it were to happen, it would most likely occur in adulthood. It’s important that any change in the appearance or feel of the skin change, such as color, texture or size, or any new symptoms, should prompt a visit to the doctor for a check-up.
