Nevus Sebaceus 

Updated: Sep 05, 2018
Author: Anwar Al Hammadi, MD, FRCPC; Chief Editor: William D James, MD 

Overview

Background

In 1895, Jadassohn first described nevus sebaceous (see the image below), a circumscribed hamartomatous lesion predominantly composed of sebaceous glands. Sebaceous nevi and verrucous epidermal nevi are closely related, and many authors regard them as variants.

Nevus sebaceus manifesting as a bald patch in a ch Nevus sebaceus manifesting as a bald patch in a child.

See 13 Common-to-Rare Infant Skin Conditions, a Critical Images slideshow, to help identify rashes, birthmarks, and other skin conditions encountered in infants.

Pathophysiology

In nevus sebaceus, postzygotic somatic mutations may result in various clinical expressions of mosaicism. Mutations in pluripotential cells may give rise to hamartomas with multiple cell lines.

Etiology

Familial cases have been reported.[1, 2, 3] Mutations in pluripotential cells during embryogenesis may generate varying lines of differentiation included in organoid nevi. Nevus sebaceus appears to respond to hormonal influences, as the lesion can be raised at birth, become flattened in childhood, and become raised again during puberty.

Deletions of the patched gene have been identified in nevus sebaceus and may be responsible for the predisposition to the development of basal cell carcinoma and other tumors in this lesion.

Epidemiology

Frequency

United States

Nevus sebaceus occurs with equal frequency in males and females of all races. Of newborns, 0.3% are affected by nevus sebaceus.

International

Sebaceous nevi are sporadic and occur with equal frequency in males and females of all races.

Race

Nevus sebaceus occurs with equal frequency in males and females of all races.

Sex

Males and females are equally affected by nevus sebaceus.

Age

Nevus sebaceus is usually noted as a solitary lesion at birth or in early childhood, whereas the characteristic features may not develop until puberty.

Prognosis

The medical importance of a solitary nevus sebaceus relates to the description of both benign change and, in some cases, malignant neoplastic change. While malignant transformation was reported in older series to occur in 10-15% of lesions, newer studies show this occurrence is certainly less than 1% and nearly always occurs after puberty. The most common malignant neoplasm arising in this disorder is basal cell carcinoma. Studies indicate that the development of basal cell carcinoma or any other malignant neoplasm is uncommon. The most frequent benign tumors are trichoblastomas and syringocystadenoma papilliferum, occurring in less than 5% of nevus sebaceus.[4]

Other benign and malignant tumors include apocrine cystadenoma, leiomyoma and sebaceous cell carcinoma. Rarely, malignant eccrine poromas, sebaceous carcinomas, and apocrine carcinomas have been reported to result in widespread metastases and death.

Patient Education

Nevus sebaceous is a rare benign tumor in children that usually presents with warty patches of hair loss on the scalp.

The development of secondary malignant neoplasms within the nevus sebaceus is rare and occurs almost exclusively in adults.

Old reports overestimate the frequency of malignant tumors. This was due to misdiagnosis of basal cell carcinomas that were in fact trichoblastomas (benign form of neoplasm that look like basal cell carcinoma histologically).

Possible signs of malignancy include ulceration or a new "bump" on the area; thus if any change is seen within the nevus sebaceous, the patients should seek medical advice.

Given the low risk of malignant transformation in children, clinical follow-up is considered to be a safe alternative to prophylactic surgical excision.

If treatment is chosen, surgical excision would be the treatment of choice; however, the timing of the surgery is controversial.

Factors to be considered include the size and location of the nevus, its cosmetic significance, and the risks and benefits of early excision (which usually requires general anesthesia) versus delayed excision (which is usually with local anesthesia).

 

Presentation

History

Most frequently, a solitary, hairless patch is noted on the scalp at birth or in early childhood. A velvety tan or orange-yellow plaque may also occur on other areas of the head and the neck.

Hormonal influences from the mother may briefly increase the prominence in an infant, whereas pubertal hormones enhance the verrucoid appearance in an adolescent.

Nevus sebaceus has a predilection for the scalp (vertex) and less commonly occurs on the face, around the ears, on the neck, or on the trunk. Nevus sebaceus occurring exclusively in the oral cavity has also been reported.[5]

Physical Examination

Nevus sebaceus passes through 3 clinically distinct stages, as follows:

  1. At birth or in early infancy, nevus sebaceus appears as a hairless, solitary, linear or round, slightly raised, pinkish, yellow, orange, or tan plaque, with a smooth or somewhat velvety surface. The nevus is usually on the scalp, often near the vertex or on the face. Extensive lesions not limited to the head have been reported.[6]

  2. In adolescence, the lesion becomes verrucous and nodular, round, oval, or linear in shape, varying in length from about 1 cm to more than 10 cm. They most commonly occur as a single lesion, but they may be multiple and extensive.

  3. Later in life, some lesions may develop various types of appendageal tumors, such as trichoblastoma; syringocystadenoma papilliferum; basal cell carcinoma; and, less commonly, nodular hidradenoma, sebaceous epithelioma, apocrine cystadenoma, eccrine carcinoma, squamous cell carcinoma, sebaceous carcinoma, spiradenoma, and keratoacanthoma.[7, 8]

An unusual phenotype with large, pink, exophytic and pedunculated nodules has been reported.[9]

The most common tumors arising within nevus sebaceous are syringocystadenoma papilliferum and trichoblastoma. A rare case of hybrid follicular cyst with matrical differentiation has been also reported.[10]

Note the images below:

Nevus sebaceus in a 4-month-old baby manifesting a Nevus sebaceus in a 4-month-old baby manifesting as nodular plaque.
Brownish wartlike plaque in a 25-year-old patient. Brownish wartlike plaque in a 25-year-old patient.
Nevus sebaceus manifesting as a bald patch in a ch Nevus sebaceus manifesting as a bald patch in a child.
Nevus sebaceus manifesting as an orange-yellow pla Nevus sebaceus manifesting as an orange-yellow plaque with a smooth or somewhat velvety surface in a 6-month-old baby.
Nevus sebaceus manifesting as a small plaque besid Nevus sebaceus manifesting as a small plaque beside a scaly scalp in a 13-year-old boy.
Linear type of nevus sebaceus. Linear type of nevus sebaceus.
Verrucous plaque in a 19-year-old woman. Verrucous plaque in a 19-year-old woman.

Nevus sebaceus lesions, especially when large, may be associated with multiple internal abnormalities, similar to those reported in linear epidermal nevus syndrome.[11]

Associated problems may include intracranial masses, seizures, mental retardation, skeletal abnormalities, pigmentary changes, ocular lesions, and hamartomas of the kidney. Mediastinal lipomatosis has also been reported.

Schimmelpenning syndrome is the combination of extensive sebaceous nevi with disorders of the central nervous system, the bone, and the eye. Some of the more common abnormalities include epilepsy; mental retardation; seizures or other neurologic defects; skeletal deformities, such as vitamin D–resistant rickets, spina bifida, bone hyperplasia, or bone hypertrophy; and ocular lesions, such as ptosis, nystagmus, optic nerve hypoplasia, and oculomotor dysfunction.

A case of linear squamous cell papilloma associated with sebaceous nevus syndrome has been described in a 7-year-old boy.

Complications

Rapid, circumscribed enlargement, ulceration, or development of an exophytic nodule should raise suspicion of malignant transformation, although the development of benign appendageal tumors is considerably more common.

The most common malignancy is basal cell carcinoma, but the incidence of this tumor has been overestimated because of misinterpretation of areas of basaloid proliferation as true basal cell carcinoma. Other malignant tumors reported include eccrine, squamous, sebaceous, and apocrine carcinomas.

 

DDx

Diagnostic Considerations

In early infancy, lesions in the scalp must be distinguished from cutis aplasia, which has a smoother papyraceous surface.

Nevus syringocystadenomatosus papilliferus may be difficult to distinguish at clinical examination, although the surface tends to be pink and nodular rather than yellow and velvety.

Early juvenile xanthogranulomas may be similar in their clinical appearance, although these generally develop rapidly into distinctive domed, papular, or nodular lesions.

Solitary mastocytomas may also be confused at clinical examination during infancy. Histologic examination clearly identifies all the disorders previously mentioned.

Congenital triangular alopecia should also be differentiated during infancy and childhood.

Differential Diagnoses

 

Workup

Histologic Findings

The epidermis shows papillomatous hyperplasia. In the dermis, the numbers of mature sebaceous glands are increased. Ectopic apocrine glands are often found in the deep dermis beneath sebaceous glands.

Frequently, small hair follicles and buds of basaloid cells that may represent malformed hair germs are present.

In childhood, the sebaceous glands in nevus sebaceus are underdeveloped, and the histologic findings may consist of only immature hair structures.

Note the images below:

Mild papillomatosis of the epidermis with sebaceus Mild papillomatosis of the epidermis with sebaceus gland lobules opening directly onto the epidermis.
Mild papillomatosis at high power. Mild papillomatosis at high power.

Staging

In the early stage, the sebaceous glands and hair follicles are hypoplastic. In the second stage, at puberty, hyperkeratosis and papillomatosis with numerous and hyperplastic sebaceous glands (diagnostic) are present.

 

Treatment

Medical Care

Photodynamic therapy with topical aminolevulinic acid has been reported to have a good response for a nonsurgical ablative treatment in a limited number of cases.

Surgical Care

The risk of malignancy is low and almost always occurs after puberty. Unless stigmatization, disfigurement, symptomatology, or a growing tumor within the lesion is present, excision is delayed until adulthood when the patient may participate in the decision.[12]

Full-thickness skin excision is usually required, and topical destruction is not recommended because it may mask malignant changes underneath the surface. Primary reconstruction is usually possible.

A 2007 study by Barkham et al concluded that prophylactic excision of all sebaceous nevi is not warranted, particularly in young children, and excision should be recommended only when benign or malignant neoplasms are clinically suspected or for cosmetic reasons.[13]

A 2014 retrospective analysis of 707 cases of nevus sebaceus diagnosed at the Ackerman Academy of Dermatopathology from 1999 to 2012 confirmed that most of the secondary neoplasms arising in association with nevus sebaceus are benign. Since no malignant tumors were seen in children, the authors believed it is reasonable to delay surgical management until adolescence.[14]

Carbon dioxide lasers have been used to treat a patient with involvement of the nose; however, the long-term risk of developing malignant transformation in any remaining deep dermal component must be considered.

Consultations

Patients should be examined for other associated findings as part of the linear nevus sebaceus syndrome. Pediatricians and other primary care providers working with the parents are usually the first to suspect or recognize neurologic or orthopedic abnormalities and to refer to the appropriate specialists. Consult a neurologist for epilepsy and other neurologic defects. Consult an orthopedist for skeletal deformities.

 

Questions & Answers