Published in Infectious Diseases in Children September 2009
13-year-old girl with lesion on scalp
by Marissa Perman, MD
A 13-year-old girl presents to your clinic stating that the mole behind
her ear extending into her scalp is changing. She states the lesion has been
present as long as she can remember and has always lacked hair. She complains
that the surface, which was previously relatively flat and smooth, has
developed a “bumpy” surface and greasy consistency over the past
several months. It otherwise remains asymptomatic.
On exam, involving the post-auricular skin and extending into the scalp
is a well-circumscribed 1 x 8 centimeter oval yellow-brown pebbly, alopecic
plaque.
Marissa Perman
Marissa L. Perman is a first-year dermatolology resident at the University of Cincinnati.
What is your diagnosis?
Nevus sebaceous of Jadassohn
Nevus sebaceous of Jadassohn is a congenital sebaceous gland hamartoma
usually found on the scalp and face. The tumor is hairless and often remains
static until puberty when sebaceous gland proliferation stimulates it to
develop a greasy surface and become thicker and more papular.
Nevus sebaceous is typically a small, solitary plaque, however some
patients may present with several or extensive lesions that can be associated
with ocular, cerebral or skeletal abnormalities and is considered part of the
nevus sebaceous syndrome discussed below.
Clinically, nevus sebaceous is present at birth, located mainly on the
scalp and face, and appears flat or slightly raised. It may be skin colored,
yellow, pink or slightly orange and vary in size. It remains alopecic for life.
During childhood, it may thicken slightly or remain stable. At puberty, it
often thickens and develops a pebbly or verrucous surface. In addition, nevus
sebaceous may develop benign secondary neoplasms including verrucae (warts),
syringocystadenoma papilliferum, trichoblastomas, tricholemmomas, sebaceous
adenomas, apocrine adenomas and poromas. These tumors are reported in 10%-30%
of lesions and are often seen in the fourth to seventh decade of life.
There has been recent literature about the risk of malignancy developing
within a nevus sebaceous, especially basal cell carcinomas (BCCs).
Previous studies reported as much as a 10% risk of developing BCCs in
nevus sebaceous, leading to the recommendation of excision to prevent
“skin cancer”. However, it is now thought that less than 1% of
lesions actually develop BCCs. The discrepancy is thought to be due to the
confusion between trichoblastomas and BCCs on histopathology ie trichoblastomas
can often be mistaken for BCCs. Other rare carcinomas include squamous cell
carcinoma, sebaceous carcinoma or apocrine carcinoma. The pathogenesis for
carcinogenesis is not known, but there is some evidence for a mutation in the
tumor suppressor gene, PTCH. Other studies have not confirmed this finding on
histopathology, classic findings are seen after adolescence and include a
papillomatous epidermis, a fibrotic papillary dermis and enlarged sebaceous
lobules with buds of immature hair cells at the dermal-epidermal junction.
Dilated glandular structures with some secretion may be found in the deeper
dermis.
The nevus sebaceous syndrome is a rare syndrome often associated with
multiple or large lesions of nevus sebaceous, often in the lines of
Baschko.
They are associated with extra-cutaneous manifestations, such as central
nervous system (CNS) abnormalities including mental retardation and seizures,
ocular malformations including colobomas and choristomas, and skeletal
abnormalities including incomplete malformation of bony structures and tissue
overgrowth. Extensive nevus sebaceous lesions and those occurring in a
centro-facial location are more likely to be associated with CNS abnormalities.
Physicians should be aware of this rare syndrome both for recognition of the
associated findings and to reassure families that the great majority of nevus
sebaceous lesions are not associated with extra-cutaneous manifestations.
Therapy is controversial due to the question of potential risk for
malignancy, as mentioned above. However, in light of the cosmetic outcome of
many of the lesions, the difficulty of clinically following lesions in the
scalp and the concern for rare malignancies, many dermatologists recommend
complete excision when the patient is old enough to tolerate local anesthesia
in an office setting. Very large lesions and those on the face may be excised
earlier during childhood when there is concern for self-esteem. The decision
for timing of excision is best made in conjunction with the family and
consideration of the circumstances of each individual child.
For more information:
- Altaykan A, Ersoy-Evans S, Erkin G, Ozkaya O. Basal cell carcinoma
arising in nevus sebaceous in childhood. Pediatr Dermatol. 2008
Nov-Dec;25(6):616-9.
- Santibanez-Gallerani A, Marshall D, Duarte A-M et al. Should nevus
sebaceous of Jadassohn in children be excised? A study of 757 cases, and
literature review. J Craniofacial Surg 2003;14:658–660.
- Sugarman JL. Epidermal nevus syndromes. Semin Cutan Med
Surg. 2007 Dec;26(4):221-30.
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