Learn About Linear Nevus Sebaceous Syndrome

What is the definition of Linear Nevus Sebaceous Syndrome?
Linear nevus sebaceous syndrome (LNSS) is a condition characterized by the association of a large, linear sebaceous nevus (type of birthmark) with a broad range of abnormalities that may affect every organ system, including the central nervous system (CNS). The nevus usually is located on the face, scalp, or neck. The most common CNS abnormalities are intellectual disability, seizures, and hemimegalencephaly (abnormal enlargement of one side of the brain). Various other CNS abnormalities have been reported. Other signs and symptoms may include various eye abnormalities; skeletal (bone) deformities; heart defects; urogenital abnormalities; and an increased risk of cancer with age. LNSS is not inherited (it is sporadic). It can be caused by a somatic mutation in any of several genes. Mutations that cause LNSS occur after fertilization and are only present in some body cells (mosaicism). Treatment is directed towards the specific symptoms in each person.
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What are the alternative names for Linear Nevus Sebaceous Syndrome?
  • Schimmelpenning Feuerstein Mims syndrome
  • Sebaceous nevus syndrome linear
  • SFM syndrome
  • Jadassohn nevus phakomatosis
  • JNP
  • Nevus sebaceus of Jadassohn
  • Organoid nevus phakomatosis
What are the causes of Linear Nevus Sebaceous Syndrome?
Linear nevus sebaceous syndrome (LNSS) can be caused by a somatic mutation in any of several genes, including the HRAS, KRAS and NRAS genes. Mutations that cause LNSS occur after fertilization (they are not inherited) and are only present in some body cells (mosaicism). These three genes belong to a class of genes called oncogenes, which when mutated, have the potential to cause normal cells to become cancerous. They play important roles in cell division, cell differentiation (the process by which cells learn to do specific "jobs") and the self-destruction of cells (apoptosis). Somatic mutations in several genes, including HRAS and KRAS, are responsible for causing isolated nevus sebaceous. It is thought that the additional signs and symptoms in people with LNSS occur because the somatic mutation affects other tissues in addition to the skin. While it is unclear exactly how mutations cause the additional symptoms of LNSS, it may relate to disrupted regulation of cell growth and division.
What are the symptoms of Linear Nevus Sebaceous Syndrome?
Linear nevus sebaceous syndrome (LNSS) is characterized by the presence of a large, linear sebaceous nevus (type of birthmark usually present from birth) with a broad range of abnormalities that may affect every organ system, including the central nervous system (CNS). The specific symptoms and severity can vary greatly from one person to another. The sebaceous nevus usually is located on the face, scalp, or neck. It can also be located on the arms, legs or trunk. While the nevus may be barely noticeable at birth, it typically becomes more pronounced with age (usually around puberty) and may appear scaly, warty or thickened. It typically does not cause any symptoms. A variety of CNS abnormalities have been reported in people with LNSS. The most common are intellectual disability, seizures, and hemimegalencephaly (abnormal enlargement of one side of the brain). Other reported CNS abnormalities include:
  • Dandy-Walker malformation
  •  abnormal formation of certain brain vessels
  •  agenesis of the corpus callosum (absence of nerve tissue that connects the two sides of the brain)
  • defects of the folds of the brain, such as a lack of folds (agyria), small folds (microgyria) or thickened folds (pachygyria).
Other signs and symptoms of LNSS may include:
  • ophthalmologic (eye) abnormalities such as "crossed eyes" (strabismus), retinal anomalies, coloboma, cataracts, or ocular hemangiomas
  • skeletal (bone) abnormalities such as cranial fibrous dysplasia, skeletal hypoplasia (incomplete formation of bones), formation of bony structures, scoliosis, or vitamin D-resistant rickets or hypophosphatemia
  • heart defects such as narrowing of the aorta (aortic coarctation)
  • urogenital abnormalities such as a horseshoe kidney
  • an increased risk of cancer with age
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What are the current treatments for Linear Nevus Sebaceous Syndrome?
Treatment for linear nevus sebaceous syndrome (LNSS) is directed towards the specific symptoms and severity in each affected person. Management may require coordinated efforts of a team of specialists that may consist of pediatricians, pediatric neurologists, dermatologists, orthopedists, ophthalmologists, and other healthcare professionals. Those who are concerned about cosmetic appearance regarding the nevus might consider surgery to remove the nevus. Surgery used to be recommended due to the risk of becoming cancerous (malignant); however, the risk of malignancy is now much less than previously believed. Surgical removal of the nevus may not always be possible due to its specific location. Additional treatments depend on the specific abnormalities present and usually follow standard guidelines in the general population for these abnormalities. For example, epilepsy may be treated with anti-seizure medications.
Who are the top Linear Nevus Sebaceous Syndrome Local Doctors?
Elite
Highly rated in
62
conditions

University Of Freiburg

Freiburg, BW, DE 

Rudolf Happle is in Freiburg, Germany. Happle is rated as an Elite expert by MediFind in the treatment of Linear Nevus Sebaceous Syndrome. He is also highly rated in 62 other conditions, according to our data. His top areas of expertise are Cutis Marmorata Telangiectatica Congenita, Epidermal Nevus, Punctate Porokeratosis, and Mosaicism.

Distinguished
Highly rated in
9
conditions

University Of Regensburg

Regensburg, BY, DE 

Christian Hafner is in Regensburg, Germany. Hafner is rated as a Distinguished expert by MediFind in the treatment of Linear Nevus Sebaceous Syndrome. He is also highly rated in 9 other conditions, according to our data. His top areas of expertise are Epidermal Nevus, Seborrheic Keratosis, Linear Nevus Sebaceous Syndrome, and Liver Spots.

 
 
 
 
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Oncology

University Of Texas MD Anderson Cancer Center

Houston, TX 

Eric Jonasch is an Oncologist in Houston, Texas. Dr. Jonasch has been practicing medicine for over 30 years and is rated as a Distinguished doctor by MediFind in the treatment of Linear Nevus Sebaceous Syndrome. He is also highly rated in 27 other conditions, according to our data. His top areas of expertise are Renal Cell Carcinoma, Chromophobe Renal Cell Carcinoma, Von Hippel-Lindau Syndrome, and Clear Cell Sarcoma. He is board certified in Medical Oncology and licensed to treat patients in Texas. Dr. Jonasch is currently accepting new patients.

How is Linear Nevus Sebaceous Syndrome diagnosed?
A diagnosis of linear nevus sebaceous syndrome (LNSS) is made by identifying the characteristic symptoms, which include a sebaceous nevus along with abnormalities affecting other organ systems. Because of the potential for multi-system involvement, anyone suspected of having LNSS should have a number of evaluations to determine the presence and extent of associated symptoms. These may include:
  • imaging studies such as CT scan or MRI of the brain (some researchers think these should be avoided unless there are signs of central nervous system involvement)
  • an electroencephalogram if epilepsy is present
  • analysis of skin biopsies
  • a complete ophthalmic (eye) exam
  • a skeletal survey
  • chests x-rays
Is Linear Nevus Sebaceous Syndrome an inherited disorder?
Linear nevus sebaceous syndrome (LNSS) is not inherited. All cases reported have been sporadic, occurring by chance in people with no family history of the condition. While LNSS is caused by genetic mutations, these mutations occur after fertilization in the affected person. They are not present in a parent's egg or sperm.
What are the latest Linear Nevus Sebaceous Syndrome Clinical Trials?
An Open Label Trial to Assess the Safety and Efficacy of Burosumab in a Single Patient With Cutaneous Skeletal Hypophosphatemia Syndrome (CSHS)
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What are the Latest Advances for Linear Nevus Sebaceous Syndrome?
Systematized Epidermal Nevus Syndrome Involving the Upper and Lower Eyelids Bilaterally
Sebaceous Nevus of the Scalp.
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Picosecond 532-nm neodymium-doped yttrium aluminum garnet laser-a promising modality for the management of verrucous epidermal nevi.