Page 56 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 2-29 Integumentary System

NEVUS SEBACEUS

Nevus sebaceus, also known as organoid nevus or nevus
sebaceus of Jadasshon, is a benign tumor that manifests
in infancy or early childhood. This tumor has a risk of
malignant transformation after puberty, and basal cell
carcinoma is the malignant tumor that most frequently Nevus sebaceus. Flesh- to yellow-
develops within these lesions. colored plaque, typically on the scalp
Clinical Findings: Most of these growths are very with associated overlying alopecia
small, and some escape detection for years. Others can
be obvious at birth. They show a large range in dimen-
sions. Most are solitary. The most common location in
which to find a nevus sebaceus is within the scalp.
Together, the scalp and face are overwhelmingly the
areas of involvement, and it is rare to find a lesion any
other place on the body. At or soon after birth, an area
of the scalp is seen to be obviously affected. Nevus
sebaceus typically start off as a thin, yellowish-brown
patch or plaque. The area is almost universally devoid
of terminal hair shafts. With time, the area becomes
more cobblestoned in appearance. These nevi are
usually asymptomatic but can be a cosmetic problem
depending on their size and exact location. They occur
in males and females with equal frequency. The lesions
enlarge in proportion to the growing child. Before
puberty, the risk of malignant transformation is very
low. After puberty, approximately one third of these
lesions develop a secondary growth, which usually
manifests as a new nodule within the nevus sebaceus.
The nodule can vary in color, but a light, translucent
purple color is not infrequently seen. It is also common
for a bleeding nodule or papule to develop within the
underlying nevus sebaceus.
Most commonly, these growths that occur within the
nevus sebaceus are benign in nature. The syringocyst-
adenoma papilliferum is the most common benign Low power. Acanthosis seen with an increased High power. Characteristic finding of the emptying
tumor to develop within a nevus sebaceus. Because of number of sebaceous glands and hair follicles of a sebaceous gland directly onto the surface of
the connection to the epidermis, these growths usually the epidermis
manifest as a draining or bleeding nodule that is slowly
enlarging. The most common malignant growth to
develop in a nevus sebaceus is a basal cell carcinoma.
These usually manifest as a pearl-colored papule with
a central ulceration and varying amounts of bleeding or
crusting. The transformation to malignancy has been
shown to increase with the age of the patient. It is
estimated that about 1% of nevus sebaceus lesions will
develop a malignant growth over the patient’s lifetime.
There have been multiple reports of various tumors
arising within a nevus sebaceus, and there have also
been reports of multiple tumors arising within the same
nevus sebaceus.
The nevus sebaceus syndrome is a very rare finding.
It is similar in nature to the epidermal nevus syndrome.
This syndrome can have a varying phenotype. The neu-
rological system, including the eye, and the musculosk-
eletal, cardiovascular, and genitourinary systems can all High power. Increased number of enlarged sebaceous
be involved to varying degrees. Patients with this syn- glands, with the central sebaceous gland emptying onto
drome usually have abnormally large areas of cutaneous the surface of the skin
involvement. The lesions can be found anywhere on the
body and are often multiple.
Pathogenesis: Nevus sebaceus is considered to be a
hamartomatous process of the epidermis and adnexal present but in reduced numbers. Prominent sebaceous with routine observation. If the nevus sebaceus develops
structures of the skin. The exact mechanism and cause glands are seen. Many of the sebaceous glands empty any areas of change, a prompt biopsy is warranted. The
have not been discovered. directly onto the surface of the epidermis. The overly- timing of the surgical removal is controversial, and
Histology: The histological picture is dependent on ing epidermis shows acanthosis and papillomatosis. The because the risk of malignancy is low, it is acceptable to
the age of the patient. Before puberty, the findings are presence of apocrine glands is often appreciated. wait until the patient is old enough to make the deci-
more subtle than after puberty. Prepubertal lesions Treatment: If treatment is undertaken, complete sur- sion. The size and location of the nevus sebaceus dic-
most commonly show undeveloped adnexal structures. gical excision is the treatment of choice. This not only tates the type of surgical excision and repair required.
After puberty, the lack of terminal hair follicles is a removes the lesion but also removes the risk of malig- Treatment of the rare nevus sebaceus syndrome requires
universal finding. Fine vellus hair follicles are often nant potential. Another approach is to watch and wait, a multidisciplinary team approach.

42 THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS