Linear nevus sebaceous syndrome

Title

Other Names:

Schimmelpenning Feuerstein Mims syndrome; Sebaceous nevus syndrome linear; SFM syndrome; Schimmelpenning Feuerstein Mims syndrome; Sebaceous nevus syndrome linear; SFM syndrome; Jadassohn nevus phakomatosis; JNP; Nevus sebaceus of Jadassohn; Organoid nevus phakomatosis See More

Categories:

Congenital and Genetic Diseases; Eye diseases; Rare Cancers; Congenital and Genetic Diseases; Eye diseases; Rare Cancers; Skin Diseases See More

Summary Summary

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).^[1] The nevus usually is located on the face, scalp, or neck.^[1]^[2] The most common CNS abnormalities are intellectual disability, seizures, and hemimegalencephaly (abnormal enlargement of one side of the brain).^[1]^[2] Various other CNS abnormalities have been reported.^[2] Other signs and symptoms may include various eye abnormalities; skeletal (bone) deformities; heart defects; urogenital abnormalities; and an increased risk of cancer with age.^[1]^[3]^[4] 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).^[5] Treatment is directed towards the specific symptoms in each person.^[6]

Last updated: 1/4/2017

Symptoms Symptoms

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).^[1] The specific symptoms and severity can vary greatly from one person to another.^[6]

The sebaceous nevus usually is located on the face, scalp, or neck.^[1]^[2] 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.^[6]

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).^[1]^[2] Other reported CNS abnormalities include:^[6]

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:^[1]^[6]^[2]

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

Last updated: 1/4/2017

The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.

Signs and Symptoms	Approximate number of patients (when available)
Adenoma sebaceum	Very frequent (present in 80%-99% of cases)
Alopecia	Very frequent (present in 80%-99% of cases)
Aplasia/Hypoplasia of the cerebellum	Very frequent (present in 80%-99% of cases)
Asymmetric growth	Very frequent (present in 80%-99% of cases)
Biparietal narrowing	Very frequent (present in 80%-99% of cases)
Cavernous hemangioma	Very frequent (present in 80%-99% of cases)
EEG abnormality	Very frequent (present in 80%-99% of cases)
Frontal bossing	Very frequent (present in 80%-99% of cases)
Genu recurvatum	Very frequent (present in 80%-99% of cases)
Hyperreflexia	Very frequent (present in 80%-99% of cases)
Intellectual disability	Very frequent (present in 80%-99% of cases)
Iris coloboma	Very frequent (present in 80%-99% of cases)
Melanocytic nevus	Very frequent (present in 80%-99% of cases)
Microphthalmia	Very frequent (present in 80%-99% of cases)
Muscular hypotonia	Very frequent (present in 80%-99% of cases)
Prominent occiput	Very frequent (present in 80%-99% of cases)
Seizures	Very frequent (present in 80%-99% of cases)
Telecanthus	Very frequent (present in 80%-99% of cases)
Vertebral segmentation defect	Very frequent (present in 80%-99% of cases)
Abnormality of vision	Frequent (present in 30%-79% of cases)
Facial asymmetry	Frequent (present in 30%-79% of cases)
Irregular hyperpigmentation	Frequent (present in 30%-79% of cases)
Plagiocephaly	Frequent (present in 30%-79% of cases)
Porencephaly	Frequent (present in 30%-79% of cases)
Aplasia/Hypoplasia of the corpus callosum	Occasional (present in 5%-29% of cases)
Cerebral calcification	Occasional (present in 5%-29% of cases)
Corneal opacity	Occasional (present in 5%-29% of cases)
Dandy-Walker malformation	Occasional (present in 5%-29% of cases)
Growth delay	Occasional (present in 5%-29% of cases)
Hyperphosphaturia	Occasional (present in 5%-29% of cases)
Ophthalmoplegia	Occasional (present in 5%-29% of cases)
Precocious puberty	Occasional (present in 5%-29% of cases)
Abnormality of dental color	-
Abnormality of dental morphology	-
Abnormality of finger	-
Abnormality of toe	-
Basal cell carcinoma	-
Coarctation of aorta	-
Coloboma	-
Cranial asymmetry	-
Hemangioma	-
Hemimegalencephaly	-
Horseshoe kidney	-
Hypophosphatemic rickets	-
Hypopigmentation of the skin	-
Ichthyosis	-
Kyphoscoliosis	-
Nevus sebaceous	-
Osteopenia	-
Overgrowth	-
Recurrent fractures	-
Somatic mosaicism	-
Sporadic	-

Last updated: 8/1/2017

Cause Cause

Linear nevus sebaceous syndrome (LNSS) can be caused by a somatic mutation in any of several genes, including the HRAS, KRAS and NRAS genes.^[5] Mutations that cause LNSS occur after fertilization (they are not inherited) and are only present in some body cells (mosaicism).^[5] 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).^[7]

Somatic mutations in several genes, including HRAS and KRAS, are responsible for causing isolated nevus sebaceous.^[5] 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.^[7] While it is unclear exactly how mutations cause the additional symptoms of LNSS, it may relate to disrupted regulation of cell growth and division.

Last updated: 1/5/2017

Inheritance Inheritance

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.^[5] 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.

Last updated: 1/5/2017

Diagnosis Diagnosis

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.^[6]

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:^[1]^[6]

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

Last updated: 1/4/2017

Treatment Treatment

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.^[6]

Last updated: 1/5/2017

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Organizations Organizations

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Foundation for Ichthyosis and Related Skin Types (FIRST)
2616 North Broad Street
Colmar, PA 18915
Toll-free: 800-545-3286
Telephone: 215-997-9400
E-mail: info@firstskinfoundation.org
Website: http://www.firstskinfoundation.org/
Nevus Network
PO Box 305
West Salem, OH 44287
Telephone: (419) 853-4525 or (405) 377-3403
E-mail: info@nevusnetwork.org
Website: http://www.nevusnetwork.org
Nevus Outreach, Inc.
600 SE Delaware Ave., Suite 200
Bartlesville, OK 74003
Toll-free: 877-4-A-NEVUS (877-426-3887)
Telephone: 918-331-0595
E-mail: http://www.nevus.org/contact-us_id45.php
Website: http://www.nevus.org/
The Skin Cancer Foundation
149 Madison Avenue Suite 901
New York, NY 10016
Telephone: 212-725-5176
Website: http://www.skincancer.org/

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Living With Living With

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Genetics Resources

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by GeneTests, the American College of Medical Genetics, and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.

Learn More Learn More

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

The New Zealand Dermatolgical Society's Web site has information on nevus sebaceous, including information on linear nevus sebaceous syndrome. Click on the link above to view this information page.
The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

In-Depth Information

Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
MeSH® (Medical Subject Headings) is a terminology tool used by the National Library of Medicine. Click on the link to view information on this topic.
The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine.
Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
PubMed is a searchable database of medical literature and lists journal articles that discuss Linear nevus sebaceous syndrome. Click on the link to view a sample search on this topic.

News & Events News & Events

News

IRDiRC Goals 2017-2027: New Rare Disease Research Goals for the Next Decade
August 10, 2017

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At what age does a child get symptoms of sebaceous nevus? See answer
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References References

Shay Menascu. Linear nevus sebaceus syndrome. Orphanet. June, 2008; http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=2612.
Pauline L, Kannan B, Saravannan V, Eswaradass VP. Linear nevus sebaceous syndrome. Ann Indian Acad Neurol. October, 2014; 17(4):468-469.
Terenzi V, Indrizzi E, Buonaccorsi S, Leonardi A, Pellacchia V, Fini G.. Nevus sebaceus of Jadassohn. J Craniofac Surg. 2006; http://www.ncbi.nlm.nih.gov/pubmed/17119437.
Santibanez-Gallerani A, Marshall D, Duarte AM, Melnick SJ, Thaller S.. Should nevus sebaceus of Jadassohn in children be excised? A study of 757 cases, and literature review. J Craniofac Surg. 2003; http://www.ncbi.nlm.nih.gov/pubmed/14501324.
Ada Hamosh. SCHIMMELPENNING-FEUERSTEIN-MIMS SYNDROME; SFM. OMIM. November 24, 2014; https://www.omim.org/entry/163200.
Schimmelpenning Syndrome. NORD. 2015; https://rarediseases.org/rare-diseases/schimmelpenning-syndrome/.
HRAS gene. Genetics Home Reference. August, 2016; https://ghr.nlm.nih.gov/gene/HRAS.