Nevus sebaceus - Hair and Scalp
Nevus sebaceus may be found on the face or neck, and less frequently, the torso or extremities may be affected. It may be multifocal following the lines of Blaschko. Extensive or multifocal lesions may be associated with the nevus sebaceus syndrome (also known as the sebaceous nevus syndrome; Schimmelpenning syndrome), where it is accompanied by neurological, ocular, cardiovascular, skeletal, and urologic abnormalities. Phakomatosis pigmentokeratotica is the presence of a speckled lentiginous nevus and a linear nevus sebaceus.
In late adolescence through adulthood, numerous secondary neoplasms may arise in a nevus sebaceus. This occurs in a small percentage of cases. They are mostly benign adnexal tumors such as trichoblastoma and syringocystadenoma papilliferum. Trichilemmomas, eccrine poromas, and sebaceomas have also developed. The most commonly encountered malignancy to arise within nevus sebaceus is basal cell carcinoma (BCC). The frequency of BCC in nevus sebaceus is thought to have been previously over-reported, with most BCC cases having been reinterpreted as trichoblastomas. Squamous cell carcinoma and sebaceous carcinoma develop very rarely, and a case each of microcystic adnexal carcinoma and melanoma has been reported.
Q85.9 – Phakomatosis, unspecified
707136009 – Nevus sebaceous
- Seborrheic keratosis
- Linear epidermal nevus
- Nevus comedonicus
- Solitary collagenoma in tuberous sclerosis
- Plexiform neurofibroma
- Solitary mastocytoma – favors distal extremities, no alopecia and positive Darier sign
- Juvenile xanthogranuloma – smooth, dome-shaped papule or nodule
- Perinatal trauma to the scalp from forceps, scalp blood sampling, or monitor electrode placement may result in scarring with associated alopecia.
- Aplasia cutis congenita presents at birth as a focal erosion or ulceration in the scalp. Lesions eventually heal with atrophy and scarring with associated alopecia. A ring of long, coarse, dark hair (hair collar sign) suggests an associated underlying neural tube closure defect.