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13-year-old girl with lesion on scalp
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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 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.